Background of the Invention The present invention relates to an automatic ai conditioner charging station for charging refrigerant and oi into air conditioner systems, such as automobile ai conditioner systems.

A number of apparatus have been provided fo automatically charging such air conditioners. Among thos are Proctor et al U.S. Patent No. 4,513,578 and Proctor U.S Patent No. 4,624,112. The former patent discloses an ai conditioner charging station having a weighing scale on whic are mounted reservoirs for oil and refrigerant, and a electronic sequencing unit, or microprocessor, which sense the weight loss of the reservoirs as first oil is charge into th e air conditioner and then refrigerant is charge into the air conditioner, the amount of each which is charge into the air conditioner being determined by an operato entering into the computer the required amounts of oil an refrigerant for a particular air conditioner. Proctor U.S Patent No. 4,624,112 discloses a system of that general type in which there is provided a conduit connecting the high an low pressure side conduits, called a cross-over conduit, an having a solenoid operated valve in it, together with solenoid operated dump valve for dumping refrigerant and oil

Sparano U.S. Patent No. 3,232,070 conducts withdraw refrigerant through a compressor and condenser, and then to drier strainer, from which it is placed into a storage tank

Taylor U.S. Patent No. 3,699,781 provides a refrigeran recovery system in which the refrigerant gas is cooled i order to remove liquid by causing condensation in a coil, prior to introduction of the refrigerant into a drier.

Koser U.S. Patent No. 4,285,206 discloses a system whi is capable of simultaneously connecting a refrigera recovery and purification apparatus to the air condition systems of two vehicles, and includes a reclaim refrigera tank mounted on a scale, and a tank for new refrigerant, o air conditioner system being recharged with recondition refrigerant while the other air conditioner system is havi the refrigerant therein withdrawn for reclaiming.

Lower et al U.S. Patent No. 4,364,236 and Lower et U.S. Patent No. 4,441,330 provide a system in whi refrigerant is withdrawn from an air conditioner and pass through a particulate filter, an evaporator, an o separator, a compressor, a condenser, and to a reservoir, a thence to a purifier, purified refrigerant from the reservo being charged into an air conditioner being serviced: microprocessor is* used to effect the- sequencing of t operations.

Goddard U.S. Patent No. 4,476,688 discloses a refrigera recovery and purification system in which refrigerant withdrawn from an air conditioner and passed through an o separator and a filter-drier by a compressor and into receiving tank for the reclaimed refrigerant. T refrigerant is delivered from the reclaim tank, for chargi into the air conditioner. A purge valve and a high pressu switch for a condenser are provided to bleed off air when a pressure in the condenser-evaporator becomes excessive. Su excess pressure causes the compressor to be shut down.

Margulefsky et al U.S. Patent No. 4,480,446 provides system for rehabilitating refrigerant including a filteri tank with a disc-shaped filter.

Taylor U.S. Patent No. 4,646,527 provides a refrigera recovery and purification system which includes a compress and an oil separator, and accumulators having heat exchan coils in them, the recovered refrigerant being placed in storage tank: in this system, distillation is utilized

separate oil and other impurities from the refrigerant.

Cain U.S. Patent' No. 4,261,178 and Cain U.S. Patent N 4,363,222 disclose a refrigerant recovery system in whi refrigerant is withdrawn and directed to a cylinder on scale: there is also disclosed a separate system in which pump produces a vacuum in a tank, which is then connect with an air conditioner in order to remove part of t refrigerant from it.

Staggs et al U.S. Patent No. 4,539,817 provides refrigerant recovery apparatus which includes a compress and filters, and a storage tank.

Saunders U.S. Patent No. 4,106,306 provides a chargi apparatus for charging a refrigeration system of the ty having a capillary tube, and discloses an electrical circu for controlling the charging, which circuit receives da relating to indoor and outdoor temperature, to suction li temperature and to suction line pressure.

There have been provided disclosures of a number o systems, for diagnosing the operation or servicing of ai conditioners.

Motl U.S. Patent No. 3,686,954 provides a system fo testing or diagnosing an air conditioner using solenoi valves actuated by manually operated switches; th temperatures and pressures of the system are measured an readouts are provided by gauges.

Suzuki et al U.S. Patent No. 4,663,940 discloses a self diagnostic apparatus for an automobile air conditioner whic utilizes an microprocessor, input signals to which includ sensing the position of dampers of air flow ducts. Also, o general interest are Hara U.S. Patent No. 4,488,409 and Iid U.S. Patent No. 4,688,389.

SUMMARY OF THE INVENTION An air conditioner charging station or apparatus i provided in which refrigerant is withdrawn from an ai conditioner, such as in an automobile, is reconditioned o

reclaimed, as by removing at least one of such extraneous contaminant elements as oil, particles of metal, and liqu refrigerant, and there is returned to the air condition being serviced substantially only reclaimed refrigerant fo that air conditioner. The apparatus includes conduits whi are connected to the high pressure and low pressure sides an air conditioner, there being in the apparatus, in serie a separator, a compressor, a condenser, and a reclaim refrigerant cylinder or tank. There are also provided a ta containing new refrigerant, and a tank or cylinder of oi all three tanks or receivers having means to measure t amount of material dispensed, such as a scale upon which th rest. To achieve the return of substantially only the sa refrigerant, after it has been reclaimed, to the a conditioner from which it was withdrawn, the amount reclaimed refrigerant delivered to or from the reclaim refrigerant cylinder has the quantity thereof measured, as determining weight added, or lost by dispensing; refrigera from the new make-up refrigerant cylinder is added to t charge to the air conditioner to the extent necessary, make up a full charge. Pressure operated switches transducers are provided at the high and low pressure sid of the compressor of the air conditioner, another at t outlet of the separator and another at the outlet of t compressor. A dump valve is provided for discharging to t atmosphere material such as non-condensible gases, which m have collected in the reclaim cylinder and/or in t condenser, the dump valve being connected to the inlet to t condenser. The reclaim cylinder is located at a lower lev than the condenser, so that such gases may rise from t reclaim cylinder to the top of the condenser, for eventu evacuation. The pressure switch at the inlet of t condenser controls, through a microprocessor, the start-up the compressor, and if there is an unsuitable differenti between the inlet and outlet pressures of the compressor,

by-pass circuit is provided for by-passing high pressur refrigerant from the discharge side of the compressor to th inlet side of the compressor, for substantially equalizin the system compressor inlet and outlet pressures. The reclaim cylinder reservoir is provided with a liqui refrigerant level sensor which sends a signal to close valve controlling the outlet from the reclaim refrigeran reservoir to close it when the level of the liqui refrigerant in the reclaim reservoir has reached predetermined low level.

The separator has a float-operated switch, which may b either a contact switch or a magnetic switch, actuated whe the float rises to a predetermined level, the switc controlling, through the microprocessor, the motor for th compressor, so that the compressor is automatically stoppe upon the accumulation of a predetermined amount of liquid i the separator. The separator includes a post dependent for a cast metal cap, a plate on the post above the floa supporting desiccant, which is thereby maintained above th liquid level. The post carries the float-operated switch The inlet of the separator is laterally of and beneath th float, so as to prevent the discharge of material, such a refrigerant and oil, into the separator from affecting th position of the float. The system includes a microprocessor which, upon receip of a signal indicating an excess pressure in the condenser causes the compressor to be stopped for a predetermined time, after which a motor driven fan for the condenser is activate and material is dumped by opening a dump valve, followed b the opening of a by-pass valve and a by-pass line around th compressor.

There is provided, also, a diagnostic apparatus, including a microprocessor which is furnished with input dat such as ambient temperature and humidity, discharge pressure, discharge temperature and suction pressure, as well a

information relative to cycling of air conditioners havi clutches. The microprocessor is also provided with ranges acceptable values for variable parameters of the a conditioner, and, more particularly, with such acceptab ranges for air conditioners based upon the automobi manufacturer and type of air conditioner in the automobil Such data is input to the microprocessor by the operator, a formulas for the establishment of acceptable ranges of valu are adjusted in accordance with an ambient factor, such humidity. The microprocessor determines the most like fault or faults in an air conditioner for a particular set actual values of such parameters as suction pressure, sucti temperature, etc., when compared with the noted acceptab ranges, and provides a signal for the likely cause or caus of a default. These possible defaults are displayed on video screen for the operator.

In an alternative embodiment, the microprocessor is al provided with ranges of acceptable values for variab parameters of the air conditioner, and, more particularl with such acceptable ranges for air conditioners based up the automobile manufacturer and type of air conditioner the automobile. Such data is input to the microprocessor the operator, and formulas for the establishment acceptable ranges of values are adjusted in accordance wi an ambient factor, such as humidity. The microprocess determines whether the air conditioner clutch is of t cycling or non-cycling type; obtains a valid set of actu values of parameters including discharge pressure, sucti pressure, and discharge air temperature, depending on wheth the system is cycling or non-cycling; and determines based such data the most likely fault or faults in the a conditioner for a particular set of actual values wh compared with the noted acceptable ranges, and provides signal for the likely cause or causes of a default. The possible defaults are displayed on a video screen for t

operator.

The microprocessor employs three systems runni simultaneously to determine whether 'the air condition clutch is of the cycling or non-cycling type and to extract valid set of actual values .of system parameters. All these systems share a plurality of registers R[l] - R[5] f storing sets of actual system values of discharge pressur suction pressure and discharge air temperature, and a fir timer and measurement means for initiating measurement of set of such data.

The first system determines whether or not the clutch cycling. It includes a first comparator for comparing t absolute value of the difference between the contents of R[ and R[n] to a preset first threshold and a second timer f generating a signal if it detects output from the comparat within a preset interval.

The second system extracts a valid set of actual valu from R[l] - R[n] for a non-cycling clutch. It includes second comparator for comparing the absolute value of t difference between the discharge pressures in R[l] and R[5 to a preset second threshold, a third comparator fo comparing the absolute value of the difference between th suction pressures in R[l] and R[5] to a preset thir threshold, a first AND gate for receiving the output of th second timer, and the first and second comparators, and first gate for providing the values in R[l] upon receipt of signal from the first AND gate. The values in R[l] represen the most recent data which meet the comparator criteria fo diagnosis. The third system extracts a valid set of actual value from R[l] - R[n] for a cycling clutch. It includes a fourt comparator for comparing the absolute value of the differenc between the discharge pressures in R[2] and R[3] to prese fourth and fifth thresholds, a fifth comparator for comparin the absolute value of the difference between the discharg

SUBSTITUTE SHSST

pressures in R[l] and R[2] to the fourth and fifth pres thresholds, a second AND gate which receives the outputs the fourth and fifth comparators with respect to the four preset threshold, and a third AND gate which receives t outputs of the fourth and fifth comparators with respect the preset fifth threshold. The second and third AND gat determine whether the discharge pressure is increasing decreasing. A flip flop receives the output from the seco timer and the second AND gate, while a fourth AND ga receives the output from the second timer, the flip flop, a the third AND gate. A second gate provides the values R[3] upon receipt of a signal from the fourth AND gate. T values in R[3] represent the first set of data which includ the maximum discharge pressure while the system is cycling. Further, there is provision for self-testing of t apparatus including both electronic and electrical componen and elements, and mechanical elements such as valve conduits and a scale. The microprocessor senses, f example, the time required for a pressure charge in conduit, and compares the sensed time with an establish acceptable time.

The microprocessor also provides, upon command, detail information for conducting a detailed check, or repair, su information being provided by the display of a substanti amount of data in relatively small type, in comparison wi the display of general operation instructional data which m be read at a distance from the video screen, as when t operator or mechanic is at the automobile making connection adjustments, etc. Among the objects of the present invention is t provision of an air conditioner charging station and meth which removes and reconditions refrigerant, and returns the air conditioner being serviced substantially on reclaimed refrigerant removed from that air conditione Another object is to provide an air conditioner chargi

station apparatus and method in which there is provided recharging of an air conditioner with substantially' on refrigerant removed from that air conditioner and reclaime and new refrigerant to the extent necessary to make up a fu recharge.

Still another object of the present invention is t provision of an air conditioner charging station in which separator is provided which has a float-operated cut-o switch for cutting off a compressor, and in which incomi refrigerant does not affect the operation of the float, an further, a separator for such a system in which desiccant supported at a level above the highest level of liquid with the separator.

A further object of the present invention is t provision of an air conditioner servicing or charging stati having a compressor and a by-pass circuit for equalizing t compressor inlet and discharge pressures.

Yet another object of the present invention is t provision of an air conditioner charging station or apparat in which evacuation of non-condensible gases is readil achieved from both a receiver for reclaimed refrigerant and condenser.

Still another object of . the present invention is th provision of an air conditioning charging station o apparatus capable of diagnosing any one of a plurality of ai conditioners, based on automobile manufacturer and ai conditioner type, and displaying to the operator probabl causes of faults in the air conditioner being diagnosed.

A still further object is the provision of an ai conditioner charging station or apparatus in which there i provided the capability of diagnosing the air conditioner fo faults, and for adjusting the acceptable ranges of values i accordance with one or more ambient factors, such as ambien humidity. Still another object is to provide an air conditione

charging station having a microprocessor and video scree with the provision of information on operating steps relatively large letters, for viewing at a distance, and f selectively displaying a large amount of detail instructions in small letters, for viewing closer to t video screen.

Other objects and many of the attendant advantages of t present invention will be more readily understood fr consideration of the following specification, claims a drawings.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is partly schematic and representationa showing a conventional air conditioner, and a chargi station or system in accordance with the present invention; Figure 2 is schematic, showing a system for sensi automatic cycling of the clutch of an air conditioning syst in accordance with the present invention;

Figure 3 is schematic, showing a system for determini valid data for non-cycling systems in accordance with t present invention; and

Figure 4 is schematic, showing a system for determini valid data for cycling systems in accordance with the prese invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to Figure 1, there is shown a convention air conditioner generally designated 10, such as is typical used in automobiles. The air conditioner 10 includes compressor 12 having a high pressure side from which flu refrigerant is conducted by a high pressure conduit 14, whi is connected to condenser 16. The discharge conduit 18 condenser 16 may pass through a receiver-drier 20, and connected to the inlet conduit 22 of evaporator 24 throu expansion valve 26. Expansion valve 26 is controlled known manner by a temperature sensing element 28 attached the suction conduit 30 extending from evaporator 24 to t

low pressure conduit 34 of compressor 12. The dischar conduit 14 is connected to the high side of compressor through high pressure conduit 36, and to the high pressu conduit 36 there is connected, through a detachable fitti (not shown) a conduit 42, forming a part of an a conditioner charging station: similarly, to the low pressu conduit 34 there is detachably connected a low pressu conduit 44 forming a part of the air conditioner chargi station. A temperature transducer 32a for sensing the temperatu of air entering the evaporator 24 is provided, as well as temperature transducer 32b for sensing the temperature of a after it has passed through the evaporator 24. There provided, also, a probe 12a for sensing the cycling of t clutch of the compressor 12.

A crossover conduit 46 is connected to the high pressu conduit 42 and the low pressure conduit 44, there being solenoid operated crossover valve 48 therein controlled by thermal transducer switch 50. A pressure operated switch transducer 52 senses high side pressure, and is connected a transformer 53, as is the solenoid valve 48. The pressu operated switch or transducer 52 is connected also to electronic sequencing unit or microprocessor 100, a part which is shown schematically near transducer or switch 5 and to the armature of a relay 55, the movable contact which is connected to the solenoid operated crossover val 48. Under normal conditions, when a suitable low pressure sensed by the pressure operated switch or transducer 52, t solenoid operated crossover valve 48 will be connected to t microprocessor 100, and to the secondary transformer 53 When an excess pressure occurs in the high pressure condui 42 and crossover conduit 46, the pressure operated switch o transducer 52 will be opened, thereby causing the relay 55 t shift so as to disconnect the solenoid operated crossove valve 48 from the microprocessor 100, the solenoid operate

valve 48 thereby being energized and the valve portion of being closed so as to close the crossover conduit 46 a prevent the fluid connected between the high pressure condu 42 and low pressure conduit 44 through the crossover condu 46. There is also provided a gauge 56 to show the high si pressure. A gauge 58 will sense and indicate the low si pressure. These gauges are electronically operated digit displays.

Thermal switch or transducer 50 senses ambie temperature and pressure switch or transducer 52 senses t pressure at the high side of the compressor 12, and activated at a selected pressure, which, for example, is 1 psig: pressure in excess of 120 psig, for example, will cau the solenoid valve 48 to close, to stop the passage refrigerant from the high side of the compressor until su time as the pressure falls below the selected amount. T solenoid valve 48 is also connected to the microprocessor 1 and receives command signals from it, as will be explain below. However, such command signals may be overridden by signal from the thermal switch or transducer 50 if ambie temperature is below a predetermined level, such as 60° F.

The air conditioner charging station 40 further compris a change of amount sensor, specifically a scale 60, whi generates signals proportional to changes in weight refrigerant and/or oil thereon and which is connected to t microprocessor 100. On the scale 60 are a reclaim reservo 62 for reconditioned refrigerant, having an inlet 61 at t top end, an outlet 63 near the bottom connected to outl conduit 64 which is connected through a solenoid valve 66 an extension 44a of the low pressure conduit 44. A float in the reclaim reservoir 62 will actuate a sensor and sign generator 67 in the bottom, which will cause solenoid val 66 to close, to prevent gas from entering outlet or delive conduit 64. A cylinder 68 for storing new make- refrigerant is also on the scale 60 and may be provided wi

a heater 70. A conduit 72 connects the make-up refrigera storing cylinder 68 to the low pressure conduit extension 4 through a solenoid valve 74 and a check valve 76 whi prevents flow of fluid from conduit 44a into the cylinder 68 Preferably there is also on scale 60 oil storing cylind 78, connected by conduit 80 to the low pressure condui extension 44a through solenoid operated valve 82 and che valve 84.

The low pressure conduit 44, 44a is connected through check valve 86 and a solenoid valve 88 to a separator 90, fo separating from gaseous refrigerant other components whic may be in refrigerant withdrawn from the air conditioner 10 including oil, liquid refrigerant and particles, such a metal particles which may have come from bearings in th compressor 12. The. separator 90, which is schematicall shown, includes a cap 92 which may be a casting of' a suitabl strong metal, there being attached to it a bowl 94 whic depends form it,a nd which is preferably transparent. Bow 94 is held to the cap 92 by any suitable releasable holdin means suc as screw threads. The cap 92 is provided with suitable hose connecting fitting for attachment to th conduit 441, and has within it an inlet conduit 96 of angula shape, having an arm 96a which extends downwardly, into bow 94 and having its discharge outlet at a relatively low level A post 98 depends downwardly from the cap 92, and has thereo a float 102 which may be caused to rise on post 98 when oi and/or liquid refrigerant has risen to a sufficient height The post 98 is hollow, and supports a sensor 104 which i engaged by float 102 when liquid in the bowl 94 has reached certain height, engagement with sensor 104 causing a signa to be sent to microprocessor 100 through conductor 106. plate 108 is mounted on the post 98, and serves to suppor desiccant, as may be provided in a small bag D, in the spac within separator 90 which will always be above the level o liquid thereon. As many bags D as necessary may be provided

and upon disassembly of the bowl 94 from the cap 92, t desiccant may be replaced.

A conduit 110 extends from the separator 90, and gaseo refrigerant leaving the separator 90 will pass through t desiccant and be dried. Because of the low temperature the gaseous refrigerant above the liquid level in t separator 90, the desiccant will be at a relatively l temperature, and will operate therefore effectively.

Oil from the refrigerant removed from the air condition 10 will be caught in the bowl 94 of separator 90, rather th being discharged. There will also remain in the bowl 9 particles and liquid refrigerant. The oil may conta refrigerant which is dissolved in it. Since the separator 9 is subject to ambient temperature, that refrigerant may bo off, and be recovered. The utilization of a transparent bo 94 will enable the operator to readily ascertain abnorm conditions relating to the oil in the refrigerant withdra from the air conditioner 10, such as whether there is no o or too little oil, or an undue amount of oil. Thus, t operator would be able to ascertain that the air condition 10 has either an inadequate supply of oil or an over supp of oil, as the case may be. With this knowledge, he c check for the reason why the proper oil-to-refrigerant rat in the air conditioner 10 is not within an acceptable rang The bowl 94 is preferably provided with a gauge, so that determination can quickly be made whether the amount of o removed form the refrigerant is within the normal range, a if so, can, upon recharging of the air conditioner 1 command the microprocessor 100 to restore the proper amou of oil to air conditioner 10 form the oil storage tank 7 Further, it will be seen that the discharge end of t conduit 96a is beiow the float 102, so that enteri refrigerant will not impact on the float 102 and alter i normal operation. The float 102 will be lifted only liquid within the bowl 94, and any foam which may be prese

in bowl 94 will not have a lifting effect on the float 10 so that thereby a true sensing of the liquid level in bowl 9 may be obtained by the sensor or switch 104.

The conduit 110 which extends form the separator 90'has pressure switch 112 connected to it, for sensing the pressur within the separator 90. A check valve 114 is included i the conduit 110 to prevent backflow of liquid or pressur into the separator 90. The placement of the check valve 11 in the conduit 110 is preferred, although check valve 114 ma be either eliminated, or replaced by a solenoid valve.

Gaseous refrigerant form the separator 90 is delivered b the conduit 110 to a compressor 116 which is driven by motor 118,m the power to which is supplied through a solenoi switch 120. The compressor 116 is of a known type, capabl of drawing refrigerant from the air conditioner 10 throug the separator 90, and compressing the received refrigerant which is gaseous. A conduit 122 serves to conduct compresse refrigerant from the compressor 116, and has connected to i a by-pass conduit 124 which extends form the conduit 122 t the conduit 110, having ^* a solenoid operated valve 12 therein. As shown by the symbol adjacent to solenoid valv 126, it will be opened by an overpressure from the condui 110, but an overpressure from conduit 122 will not open it so that only when solenoid valve 126 is opened throug energization of the solenoid will it be opened an refrigerant be permitted to flow through the by-pass condui 124.

A solenoid operated dump valve 128 is connected to th conduit 122, and there is provided in the conduit 122 solenoid operated control valve 130. Also in conduit 122 i a pressure switch 132.

Conduit 122 delivers reclaimed, purified and compresse refrigerant to the condenser 136 which is diagrammaticall illustrated as comprising a coil: a fan 138 driven by a moto 140 may be caused to blow air across the condenser 136

Condensed refrigerant is delivered through conduit 142 havin a solenoid valve 144 therein to the receiver 62, the condui 142 extending downwardly because the receiver 62 is locate at a lower level than the condenser 136, the conduit 14 entering the upper part of the receiver 62.

In operation, the conduits 42 and 44 are connected to th air conditioner 10, and it is assumed that the solenoid valv 48 is closed; it is opened by microprocessor 100 only whe charging refrigerant from either the reclaim cylinder 62 o make-up; cylinder 68, or when dumping the charge of ai conditioner 10, unless it is being closed by the sensing o abnormal temperature by the thermal switch or transducer 5 or abnormal pressure as sensed by the pressure switch o transducer 52. The solenoid valve 88 will be closed, and i the pressure switch 112 which senses the pressure in condui 110 connecting the separator 90 with the compressor 116 is i the range of 15 to 20 pounds per square inch, pressure switc 112 will cause motor 118 and compressor 116 to be activated When the pressure falls to approximately 0 psig, solenoi switch 120 will be opened, and the compressor 116 will stop However, the signal from switch 112 passes through microprocessor 100 to the solenoid switch 120 (or it equivalent) and under certain circumstances, the signal fro pressure switch 112 may be overridden or by-passed, so that for example, when it is necessary to have the compressor pul a vacuum on the air conditioner 10, this may be effected b the overriding or by-passing by the signal form pressur transducer 112.

The purpose of the by-pass conduit 124 is to equalize th high and low pressure sides of the compressor 116 since know air conditioner compressors cannot start if there i differential between the low pressure side and the hig pressure side which is too great. A compressor without suc limitation would not need the by-pass conduit 124. Th pressure on the high pressure side of the compressor 116 i

sensed by the pressure switch 132 and the pressure on the l pressure side of the compressor 116 is sensed by the pressu switch 112, the signals from these switches being deliver to the microprocessor 100 for processing, and the controlli of the valve 126, to open it, to thereby permit t equalization of the pressures on the high and low pressu sides of compressor 116: when the microprocessor 100 caus the solenoid valve 126 to be opened, to unload the compress 116, the dump solenoid valve 128 and the solenoid valve 1 in the conduit 122 are both closed. The result is that on small volume of refrigerant flows from the high pressure si of compressor 116 to the low pressure side, and there is n introduced into the conduit 122 refrigerant from t condenser 136. When the compressor 116 is not bei unloaded, the by-pass solenoid .valve 126 is closed and t solenoid valve 130 in the conduit 122 to condenser 136 wil be opened. When compressor 116 is restarted, contro solenoid valve 130 is opened shortly after by-pass valve 12 closes. In overall operation, the compressor 116 withdraw refrigerant from the air conditioner compressor 12, th refrigerant flowing through the separator where oil particles, such as metal particles, and liquid refrigeran are removed, with reconditioned gaseous refrigerant the flowing to compressor 116 where it is compressed an delivered to the condenser 136, where it is condensed, an caused to flow into the receiving tank 62 for the withdraw and reconditioned refrigerant. The microprocessor 100 wil determine the difference in the weights on the scale prior t the introduction of the withdrawn and reconditione refrigerant into the receiving tank 62. That withdrawn reconditioned refrigerant will pass to the compressor 12 o the air conditioner 10 upon the opening of solenoid valve 6 and the closing of the solenoid valve 144 in the conduit 14 leading to the intake of the receiving tank 62. Thus, ther

will be returned to the compressor 12 from the receiving ta 62 substantially only refrigerant which was withdrawn fr compressor 12. In this way, any contamination which may present in the refrigerant from one air condition system in one automobile will not be mixed with refrigerant fr another automobile, so that there is thereby avoided t transfer of contaminants form one air conditioner system another. Thus, substantially only the same recondition refrigerant is returned to the air conditioner from which is withdrawn, and, with the following exception, refrigerant from another air conditioner is placed into t air conditioner being serviced. That exception is that very small amount of refrigerant from a servicing operati on one vehicle air conditioner may remain in the condens 136, and that very small amount will be delivered to t receiving tank 62 upon the initiation of servicing of second air conditioner of a second automobile. However, th amount of refrigerant is so small that any contamination wi be negligible, due to the extremely small amount contaminant that may -be delivered into the air conditioner the second vehicle.

If during operation the float 102 rises and strikes t sensor 104, a signal by way of conductor 106 to t microprocessor 100 causes the circuit to motor 118 to broken, and compressor 116 will stop. There is provided transparent switch button 115 with a light behind it whi flashes at this time, there being provided adjacent to it legend that the lighted button is to be depresse Depression of this lighted button-switch will cause t microprocessor to close the solenoid valve 88 and to cau the compressor 116 to operate, to reduce the pressure with the separator 90, the solenoid valve 88 preventing t addition of more freon to separator 90: when the pressure separator 90 is satisfactorily reduced to approximately psig, this will be sensed by the switch 11, which wi

provide a signal to microprocessor 100, which will then sh down compressor 116. After that, the bowl 94 may be remov from the cap 92, the bowl emptied and cleaned, and t desiccant bag D replaced. In some instances, a part of the normal refrigera charge of a particular air conditioner may have leaked ou so that the amount of withdrawn, reconditioned refrigera delivered to the receiving tank 62 is not sufficient provide .a complete charge for the air conditioner bei serviced. To provide a complete charge, the amount of t deficiency is determined, as explained herein below, and t necessary amount of refrigerant to provide a full charge withdrawn from the make-up refrigerant cylinder 68. Thu the air conditioner 10 will receive a full charge made up one or a first component, which is the same refrigerant th was withdrawn from the air conditioner 10,a nd which w reconditioned by the separator 90, and to the exte necessary, a second component of new refrigerant form t make up cylinder 68. As is known, a small amount of oil usually introduced into the air conditioner durin recharging, and this is provided form the oil storage ta 78, through conduit 80 when the solenoid valve 82 is opened.

Returning to Figure 1, the dump solenoid valve 128 i provided to permit dumping of material to atmosphere. Tha material may be non-condensible gas, which in most cases i air, which may have been contained in the withdraw refrigerant. That air would be located in the upper o higher part of the condenser 136, at and near the inle thereof. This non-condensible gas, or air, would have rise from the liquid refrigerant in the coils of the condenser 13 to the highest part of the condenser coil: liquid, being o higher density, being in the lower part of the coil o condenser 136. With the compressor 116 stopped, the solenoi by-pass valve 126 will be closed, the condenser valve 13 will be opened, and the dump valve 128 will be opened. Sinc

the condenser 136 is at a higher elevation than the receivin tank 62, any gas which will have accumulated in the receivin tank 62 will, with solenoid valve 144 opened, pass upwardl to and through the condenser coil 136, since the receivin tank 62 is below the condenser 136: that non-condensible gas or air, will thus, also, be exhausted form the apparatu through the dump solenoid valve 128. This will avoid th incorporation of non-condensible gas, such as air, in th refrigerant which is returned to the air conditioner 10 whic is being serviced.

Purging occurs when an excessive pressure, which may b approximately 325 psig, is sensed by the pressure switch 132 When this level of pressure is sensed, the compressor 116 i stopped _τ by interrupting the flow of current to the moto 118, and after a time delay, the microprocessor 100 cause the motor 140 to drive, fan 138 and causes the condense solenoid valve 130 and the dump solenoid valve 128 to open t permit the above described dumping function. The pressur buildup in the condenser 136 will be caused, for example when the receiving tank 62 is substantially full, when it ma contain some air, together with the withdrawn an reconditioned refrigerant in the liquid state. When th receiving tank 60 is full, no more refrigerant can be pumpe into it, so that continued operation of the compressor 11 will cause the noted rise in pressure. Also, if th receiving tank 62 is substantially full, and the temperatur rises, the refrigerant in the receiving tank 62 will expand and since the solenoid valve 66 in the outlet conduit 64 i closed, refrigerant must flow out of receiving tank 62 to th condenser 136. This is permitted by the solenoid valve 14 which permits an override as indicated by the symbol adjacen to it, the higher pressure in the receiving tank 62 forcin the valve off of its seat and refrigerant and/or air passin upwardly to the coil of condenser 136. Valve 144 is normall open, except when the apparatus 40 is dispensing oil o

refrigerant. The condenser 136 will have part of its coil coils filled with liquid, but also part thereof will filled with high pressure gas. For this reason, there space in the condenser 136 to accept overflow liqu refrigerant from the receiving tank 62. Any gas, as abov explained, will rise upwardly to the top portion of the co or coils of accumulator 136, and be adjacent the inlet, a will be discharged, as above indicated, during the dumpi phase. Turning now to the operation of the apparatus includi the microprocessor, it will be understood that the chargi station or apparatus 40 will include necessary switches, su as a main on/off switch, as well as a video display, vario signal lights, and a key pad or pads for the entry o commands.

When the apparatus 40 is turned on, a menu will b displayed on the video screen as follows: Dump and reclaim Dump to atmosphere Service

2 oz. shot Diagnose Self-test The operator may choose the "Dump and reclaim" operation and on command, refrigerant will be withdrawn from th compressor 12 of the air conditioner 10, passed throug separator 90, compressor 116, condenser 136 and to th receiving cylinder 62. When the suction pressure reaches psig, the apparatus will stop and that operation will hav been completed.

If the operator chooses "Dump to atmosphere", th condenser solenoid valve 130 will be closed and the dum solenoid valve 128 will be opened, and the refrigerant wil be withdrawn from the air conditioner 10 by compressor 116 passing through separator 90, and will dump to atmosphere

the operation continuing as before, until the pressure of th system is 0 psig, as sensed by pressure transducer 112. Thi operation will then stop.

In utilizing either the "Dump and reclaim" or the "Dum to atmosphere" modes, if, as sometimes happens, the pressur sensed by pressure transducer 112 rises, the compressor 11 will again be activated. In both of these operations, sinc the withdrawn refrigerant passes through the separator 90 the operator will be enabled to visually inspect the remove oil through the transparent, bowl 94 to determine an abnormalities, as an aid to diagnosing any faults in the ai conditioner 10. It is noted that the machine does not tur off when the compressor is stopped during these operations but remains active so that any rise in pressure will b sensed. Such pressure rise may be due, for example, t effervescence of the refrigerant form the oil in the system.

If the "Service" mode is selected there is displayed o the video screen a menu of instructions for the operato requiring him to enter the length of time that the evacuatio of the air conditioner system is to proceed, the amount o oil to be charged into the air conditioner, the amount o refrigerant to be charged into the air conditioner, an whether the operator wishers to interrupt operations afte the evacuation of the air conditioner in order to evaluat the air conditioner for leaks. It will be understood tha this service operation will follow either the above describe "Dump and reclaim" operation or "Dump to atmosphere operation. If the operator does not choose to "dump" bu enters a requirement for vacuum, the apparatus automaticall performs a "Dump and reclaim" function before performing t vacuum function. The operator can cause the function to b "Dump to atmosphere" or "Vacuum to atmosphere" if he s chooses.

There is also displayed to the operator an option o adding a small amount of refrigerant, such as 2 oz., aft

the air conditioner has been charged with refrigerant fro either receiving tank 62 or make-up refrigerant storage tan 68, or both. This operation may also be performed after th air conditioner 10 has been evacuated, so that it is charge with refrigerant in order that it may be tested for leaks.

The "Diagnose" operation permits the operator, with th aid of the apparatus 40, to diagnose the vast majority o automobile air conditioners now in use to determine if the are functioning satisfactorily, or if not, to determine th cause of the malfunction. Air conditioners can be diagnose by observing the ambient, inlet, and discharge ai temperatures; the suction and discharge pressures; and th relative humidity. These parameters can be compared t expected values to identify most malfunctions. However, many automotive air conditioners regulate thei output by cycling the clutch on and off via an electri clutch. In these systems, the suction and discharge pressur change dramatically when the clutch cycles on and off. Whe the compressor runs, the suction pressure decreases and th discharge pressure increases. Conversely, when th compressor is not running, the suction pressure increases an the discharge pressure decreases. For example, a typica system might see the suction pressure change from 50 pound to 30 pounds in two seconds when the clutch turns on, an increase from 18 pounds to 30 pounds in two seconds when th clutch turns off. The most accurate diagnosis can be done i the pressures at the end of the clutch cycle are used. Th objective is to obtain a set of data that is best indicativ of system performance. This objective can be accomplished by measuring th clutch voltage, _t continuously monitoring the pressures, an using the last values observed before the clutch turns off.

When the "Diagnose" function is selected, the vide screen will give such instructions as to connect th diagnostic sensors. These are the evaporator input ai

temperature from the transducer 32a and the evaporat discharge air temperature from the transducer 32b. I addition, an ambient humidity transducer 150 will have be connected to the microprocessor, as well as an ambie temperature transducer 152. The operator will be instruct to start the engine and set it at a selected R.P.M. He then instructed to check all of the air conditioner contro and to connect the probe 12a to the clutch of the compress 12, so that the microprocessor 100 will receive signa indicative of the cycling of the clutch of compressor 1 The controls are required to be set for maximum co temperature, and the blower (not shown) of the ai conditioner 10 to be placed at its highest speed. Also, t operator will be instructed to open both front doors of t automobile, and then to signal the microprocessor 100 wh these steps have been accomplished. The diagnosis is th performed, as will be described hereinbelow.

However, measuring clutch voltage is not always practical solution because the clutch wires are not alwa easily accessible. An indicative set of data can also attained by monitoring the suction pressure, and usi measurements taken when the suction pressure is at a minimu since the suction pressure is minimum when the clutch tur off for most air conditioning systems. However, this do not work for expansion valve thermostatic switch system since the suction pressure is not at a minimum when t clutch turns off.

The preferred method of obtaining a set of data is monitor the discharge pressure, and use measurements tak when the discharge pressure is at a maximum, since when t clutch turns off, the discharge pressure is maximum stabilized for all known automotive air conditioning system Ideally the diagnostic system would automatically detect t large, regular variations in discharge pressure and if t air conditioner has a cycling clutch, use variables measur

when the discharge pressure is maximum to perform t diagnosis.

Some other automobiles have a separate cooling fan f the air conditioner that cycles on and off, controlling t air conditioner's discharge pressure (and to a lesser exten the suction pressure). For these cars, the dischar pressure increases when the fan is off and decreases when t fan is on. The change in discharge pressure can be ve large — perhaps 100 pounds -- but the rate of change is mu more gradual, roughly approximating a sinusoid. Changes i suction pressure are much less dramatic and ar correspondingly less important. For these cars, it i desirable to use the discharge pressure just as the cooli fan turns on, i.e., the maximum discharge pressure. This objective can be accomplished by measuring the fa voltage, continuously monitoring the pressures, and using th last values observed ^" before the fan turns on. However, thi solution requires extra hookups for the mechanic which may b difficult. The preferred _^ method of obtaining a set of data for thes systems is to monitor the discharge pressure, and use value measured when the discharge pressure is maximum. Ideally the diagnostic system would automatically detect the larg regular variations in discharge pressure and if the ai conditioner has a cycling fan, use variables measured whe the discharge pressure is maximum to perform the diagnosis.

Finally, some cars do not have a port where discharg pressure can be conveniently observed. In these cases, th diagnosis should be performed without knowing the discharg pressure, if possible.

When the diagnostic function is requested, the mechani is asked several questions such 'as type of car, type of ai conditioner, etc. The last question asked is whether he ha connected the discharge pressure hose or wishes to ignore th discharge pressure. If he chooses to ignore the discharg

pressure, the system will monitor the remaining variabl (relative humidity, inlet air temperature, ambient a temperature, discharge air temperature, and sucti pressure). If these variables indicate that the system performing normally, the discharge pressure is assumed al to be normal and the mechanic is informed that the system functioning normally. However, if the monitored variabl indicate the system is malfunctioning, the mechanic is giv the probable causes of error assuming the discharge pressu is too high, too low, and within normal limits. So alternative implementations could automatically sense th the discharge pressure is not connected based on the make a model of automobile, absence of fluctuations in dischar pressure, etc. However, these are all inferior becau asking the mechanic to provide this information allows t system to remind the mechanic that the diagnosis is le accurate, and because it places the mechanic in control the machine.

Referring now to Figure 2, there is shown a system f automatically detecting whether "the air conditioning syst is cycling or non-cycling is described. This system wor while monitoring nothing but discharge pressure (or, discharge pressure is disabled, suction pressure), and wor reliably on all known automobiles. Only discharge pressures will be discussed, sin operation is similar if the suction pressure is monitored.

As shown in Figure 2, the system uses a timer, TI, initiate a set of measurements. This timer puts out "convert" pulse at a regular interval. The interval can set for almost any time. Through experimentation, we ha found that an interval of approximately .75 seconds convenient.

The timer TI triggers a measurement device M, such as analog to digital converter, to quickly measure the set data that might be changing. Each set includes a measureme

of discharge pressure and suction pressure. Optionally, ea set can contain other measurements that might vary on cycli systems, such as discharge air temperature.

The measurement of discharge and suction pressure must quick enough that there is no appreciable change in eith measurement until both measurements are made. For exampl assume that discharge pressure is measured first, th suction pressure. The measurements must be fast enough th if the discharge pressure happens to be measured at the ve end of the clutch cycle on a cycling clutch air conditione the suction pressure has not significantly increased when is measured. In practice, a good diagnosis can be achiev if the suction pressure has increased one less than one pou during this measurement interval. When the measurement is completed, the measurement devi M sends a "done" strobe that stores the measurement in a ba of registers R[l] - R[n] . At the end of each measuremen the result of the measurement is placed in R[l] . The o contents of R[l] are placed in R[2] . The old contents R[2] are moved to R[3] , and so on until the old contents R[n-1] are moved to R[n] , and the contents of R[n] a discarded.

A comparator device Cl is connected to two registers a monitors the discharge pressure dp (or suction pressure s in these two registers. Specifically, comparator Cl monito whether the absolute value of the difference between t discharge pressure dp of the two registers exceeds a pres threshold. Figure 2 shows the comparator Cl monitoring t absolute value of the difference between the dischar pressure in registers R[l] and R[5] with respect to a pres first threshold. Although the discharge pressure in R[l] c be compared to the discharge pressure in any register R[χ] where x is greater than 1 and less than or equal to n, t threshold can be set to any level. In practice, if TI has a interval of .75 seconds, a threshold of 8 pounds fo

ESHEET

discharge pressure and 3 pounds for suction pressure wo well. It is apparent that, for the example shown, t comparator output signal indicates that the dischar pressure has changed more than 8 pounds in 3 seconds. Th signal indicates that the air conditioner might be cycling.

A second retriggerable timer, T2, is also used. T interval of this timer can be set to a wide variety values. For the illustration in Figure 2, a value of seconds works well. This timer sets its output ("cycling" whenever the input (R[l] not equal to R[5] ) has turned within the last 75 seconds. If a large change in pressure detected once every 75 seconds (or faster), the T2 outp will remain high (i.e., will be 1) continuously, indicati the air conditioner is cycling. If the pressure is general stable, the T2 output will remain low- (i.e., will be continuously, indicating the air conditioner is non-cyclin If the change in pressure temporarily exceeds the comparat threshold (as might happen when the automobile is fir started or if the mechanic quickly changes the engine RPM the T2 output temporarily goes high, but reverts to its lo non-cycling state after 75 seconds.

It is obvious that this simple system can give incorre results if the discharge pressure increases, then decrease then increases again between the measurement in R[l] a R[5] . However, for the values shown, the pressure would ha to have two maximums within 3 seconds for this to be problem. Practical air conditioners are not capable of wi pressure swings at such fast rates.

It should be noted that pulsations from piston-ty compressors are not a factor because the long hos connecting the automobile system to the machine and t plumbing in the machine effectively dampen these hi frequency pressure variations.

A system for determining valid data for non-cycli systems is shown in Figure 3. The timer TI, measureme

device M, and registers R[l] - R[n] are the same as discusse above with respect to Figure 2. The comparators C2 and C are similar to the one discussed above but have differen thresholds. The comparator outputs are logically ANDed i the AND gate Al. The AND gate output indicates valid data.

When a diagnosis is desired, all registers are cleare (but the timer T2 discussed above is not cleared). Afte five intervals, registers R[l] and R[5] both contain data The data are valid if the absolute value of the difference o the two discharge pressures dp is less than the discharg threshold, the absolute value of the difference of the tw suction pressures is less than the suction threshold, and th system is not cycling. If any of these conditions is no met, another measurement is taken in .75 seconds and th compare operation is repeated. A gate Gl provides the mos recent data that meets the comparator criteria for diagnosis Convenient values for discharge and suction thresholds ar four and two pounds, respectively. Also, the discharge an suction pressures in R[l] can be compared to the discharg and suction pressures in any register R[y] , where y i greater than 1 and less than or equal to n; y can be the sam as or different from x.

It is evident that this system returns the first set o data where the discharge pressure has changed less than pounds in 3 seconds and the suction pressure has changed les than 2 pounds in 3 seconds while the system is non-cycling.

The system for determining valid data for non-cyclin systems is shown in Figure 4. The timer TI, measuremen device M and registers R[l] - R[n] are the same as discusse above with respect to Figures 2 and 3.

Comparator C4 presents the "increasing" signal if th discharge pressure dp in R[l] minus the discharge pressure d in R[2] exceeds the ARM threshold; and presents th

"decreasing" signal if the absolute value of the discharge pressure in R[2] minus the discharge pressure in R[l] exceeds

the TRIGGER threshold. Comparator C5 similarly compares th discharge pressures dp in R[2] and R[3] . The ARM and TRIGGE thresholds can be set to any reasonable value. In practice the device works well if both comparators have an AR threshold of 1 pound and a TRIGGER threshold of 2 pounds.

The comparator outputs are logically ANDed in the AN gates A2 and A3. The output of A2 indicates the discharg pressure increased for two measurements in a row — that is the discharge pressure in R[l] exceeds the discharge pressur in R[2] by two or more pounds and the discharge pressure i R[2] exceeds the discharge pressure in R[3] by two or mo pounds. Similarly, the output of A3 indicates the dischar pressure has decreased for two measurements in a row.

The output of AND gate A2 sets a flip-flop FF, the outp of which indicates an ARMED state. The flip-flop is reset, i ^• the air conditioner is not cycling. It is evident that t device is ARMED if the air conditioner is cycling and t discharge pressure is increasing.

The output of AND gate A4 presents data from regist R[3] for diagnosis if the discharge pressure is decreasi while the device is ARMED and the air conditioner is cyclin

When a diagnosis is desired, all registers and the ARM flip-flop FF are cleared (but the timer T2 discussed above not cleared). After three intervals, registers R[1J and R[ both contain data. When the discharge pressure star increasing, the comparators C4 and C5, AND gate A2, and t flip-flop FF switch the device into the ARMED state. Wh the discharge pressure reverses and starts decreasing, t comparators C4 and C5, AND gate A3, and AND gate A4 open t GATE G2 and present the data from register R[3] f diagnosis.

It is evident that when the gate opens, the dischar pressure in R[3] represents the maximum discharge pressur As previously described, all compare operations occur eve measurement interval (.75 seconds) until a maximum is foun

Therefore, the system in Figure 4 returns the first set data that includes the maximum discharge pressure while t system is cycling.

To form a useful diagnostic system, the functions Figures 2, 3, and 4 are all run simultaneously. For econo of the system, the registers R[l] - R[n], timer TI, a measurement device M can be shared. When the mechani requests diagnosis, the system in Figure 2 determines whethe the air conditioner is cycling or non-cycling. The system i Figure 3 will continuously look for stable data and, i stable data is found, will present the data for diagnosis i the system is non-cycling. The system in Figure continuously looks for data that includes the maximu discharge pressure (or by using different comparators, th minimum suction pressure). It will present the first set o data that includes a maximum discharge pressure if the .ai conditioner is cycling.

Once a set of data is presented for diagnosis, the dat from ^' this device and the slowly-varying data (such a relative humidity and ambient temperature) are used t perform a diagnosis. The diagnosis is presented to th mechanic. The circuits in Figures 3 and 4 are reset (but th cycling timer T2 in Figure 2 is not reset), and a new set o data is searched for. It is evident that this device continuously an automatically detects cycling and non-cycling ai conditioners, presenting the best possible data fo diagnostic evaluation. Further, if the device incorrectl determines whether the air conditioner is cycling (such as i the mechanic quickly changes engine RPM), the device wil automatically correct its error and present correct data fo the next diagnostic evaluation.

The diagnosis is initiated in a manner similar to tha described above with respect to systems in which the clutc wiring is easily accessible. When the "Diagnose" function i

selected, the video screen will give instructions to connec the evaporator input air temperature transducer 32a and th evaporator discharge air temperature transducer 32b. Th ambient humidity transducer 150 and the ambient temperatur transducer 152 will have been connected to th microprocessor. Suction pressure is monitored by pressur transducer 112, and discharge pressure is monitored b pressure transducer 52. The operator will be instructed t start the engine and set it at a selected R.P.M. He is the instructed to check all of the air conditioner controls. A previously described, the controls are required to be set fo maximum cold temperature, and the blower (not shown) of th air conditioner 10 to be placed at its highest speed. Th operator will be instructed to open both front doors of th automobile, and then to signal the microprocessor 100 whe these steps have been accomplished. The diagnosis the proceeds as follows.

The video screen will signal if the ambient ai temperature is outside a preselected range (of between 60° and 120° F), which is the suitable temperature range fo conducting tests. If there is sensed a condenser discharg pressure which is too high, such as above 350 psig, thi excessive pressure will be displayed on the video screen wit instructions to stop the test and correct the problem. Also if the evaporator or suction pressure is excessive, such a above 150 psig, this information will be displayed wit instructions to stop the test and to check hose connections Assuming that these parameters are within acceptable limits there will be displayed the names of various automobil manufacturers, and the operator will enter a signa designating the manufacturer of the automobile of which th air conditioner 10 under test is a part. There will then b displayed a menu providing different types of air conditione systems which are in use including, by way of example systems which have an expansion valve and a thermostati

switch, and a system having an expansion valve with pressure switch. The operator will then enter into t register a signal representative of the type of a conditioner system under test. The microprocessor wi recognize whether the entered vehicle make and entered a conditioner type are conventional, known combinations, not. If a selection has been made of, for instance, manufacturer and a system type which stored data recogniz as not being a known combination of data, the video scre will advise the operator that he has chosen an unusu combination of these data and ask if he wishes to change t selection. The operator is then given an opportunity to r enter his selections of vehicle manufacturer and a conditioner type, and this matter is corrected, if needed. The microprocessor 100 has stored within it an acceptab range of ambient temperature for conducting tests, and f each combination of. car make and air conditioner type, range of typical acceptable operating values, specificall suction pressure, discharge pressure, discharge ai temperature, and voltage and/or amperage of the clut cycling probe 12a. The microprocessor 100 adjusts the values to correct for ambient temperature and/or humidity provide an ambient adjustment factor for the acceptable ran of values. In particular, formulas have been developed, and a known to workers skilled in the art, of the acceptable range of these values. Discharge pressure value range i established by multiplying the ambient factor b approximately 2.55, plus or minus 20 psig. The acceptabl suction pressure value range is established by the ambien factor multiplied by 0.5, minus 17,a nd plus or minus 5 Discharge air temperature value range is established based o the ambient factor times .03 plus 19, plus or minus 4, or 32 plus or minus 4. However, it is now recognized that thes relationships, to provide acceptable ranges of temperatur

and pressure, should be modified on the basis of the ambien relative humidity. Therefore, the microprocessor 10 provides for modification of the ambient temperature facto in these relationships, so as to increase them as humidit increases above 30%. There is no modification if th humidity does not exceed 30%, there is a 5% increase in t ambient temperature factor if the humidity is between 30% a 50%; there is an increase of 11% if the ambient relati humidity is between 50% and 70%, and if the ambient relati humidity is above 70%, the temperature factor is increased b 16%.

The microprocessor 100 programmed for the particula automobile manufacturer and air conditioner system type unde diagnosis will then be supplied form the sensors with data above noted, including ambient temperature and humidity, a will establish the acceptable discharge pressure range, t acceptable _^ suction pressure range, and the acceptabl evaporator discharge air temperature range, these acceptab ranges being varied, as above noted, where the sensed ambie relative humidity is above 30° There is provided below portion of a chart which is representative of a look-up tabl forming a part of the microprocessor 100. It will understood that this representation is for a particular ty of particular types of air conditioner and there would other and different charts for other types of air condition within microprocessor 100:

IF 0.220 CCOT/THERMOSTATIS SWITCH

^•

As will be apparent, there are many different resulting situations, the numerals in the right hand column being, in effect, commands to display on the video screen the diagnosed fault, or, in the case of numeral 315, that there is no fault diagnosed. There is provided below a table of numerals and displays associated with each:

ALL DISPLAYS

301 Ambient temperature is (110). Diagnostic evaluation is only valid from 60F to 120F.

302 Is the ambient temperature probe lcoated in front of the condensor.

303 If temperature reading is incorrect replace the probe.

304 Discharge pressure is (111).

305 Is condensor air flow restricted?

306 Over charge of air in the system - DUMP, EVACUATE AND RECHARGE. PRESS "PROCEED"

307 PROCEED (1) (IF "PROCEED" display service screen go to dump and reclaim mode. When pump is "OFF" (0-PSIG) for 10 seconds, proceed into the charge sequence-return to diagnosis. )

308 Check blower for low air flow

309 Suction pressure is (112)

310 Discharge air temperature is (113)

311 Is the discharge temperature probe properly located?

312 Is hose connection secure and schrader depressed?

313 System low on charge - If charge is required press "PROCEED"

314 PROCEED (2) (IF "PROCEED" display evacuate and charge screen. When completed return to the diagnosis mode (add a line on the screen) )

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315 System diagnosed as normal.

316 Defective evaporator pressure control valve. (EPR-POA-STV-)

317 Defective expansion valve

318 Restricted receiver dryer

319 Pressure switch not functioning properly.

320 Compressor or clutch malfunction.

321 Restricted orifice tube

323 Defective thermostatic switch

324 Check compressor control valve and O rings.

325 Expansion valve stuck open

326 No power to the clutch

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By using of the microprocessor, and the inputting o data, the operator will be advised of the condition of th air conditioner under test, whether it is satisfactory or, i not, the probable causes of the malfunctions. If, upon display of the initial menu, the operato selects the "Self-test" function, the program of th microprocessor determines if signals are passing to and bein received by the components intended, and in the prope sequence; there is also a testing to determine if thes components respond in the manner required, that is, fo example, if a solenoid operated valve is signalled to move t the open position, whether it does so. By signals from pressure transducer or switch adjacent to a solenoid valve, the microprocessor 100 can determine if the valve opens o not, and/or if the related conduit is open or blocked o partially blocked,since it will determine the time require for a drop in pressure of a certain amount, and a sensin that the pressure drop is less than the predetermined amoun with a predetermined time will provide an indication of malfunction in this mechanical part of the apparatus. Similarly, a part of the operatio ^' n is the discharging o refrigerant from the make-up refrigerant storing tank 68, a for a period of time of two seconds, the microprocessor 10 sensing if the weight loss or amount discharged in that tim is substantially equal to a predetermined weight loss o amount discharged, and if not, there will be an indication o malfunctions such as a problem with the scale 60 or alternat amount-determiner such as a flowmeter or a malfunction of th solenoid valve 74, conduit 72, etc. Thus, not only is ther a self-checking of the electrical components, but also o mechanical components by the microprocessor 100.

Another function of the microprocessor 100 is a "Help function. The operator may not be aware how a test of th air - conditioner 10 should be conducted. He can go to th apparatus 40,and key into the microprocessor 100 a signal fo

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"help". The microprocessor will then display detailed instructions on, for example, how to determine if an expansion valve forming a part of the air conditioner 10 is operating satisfactorily. As the detailed instructions often contain a substantial amount of information, the microprocessor will reduce the size of the letters in order to display more information on the video screen than could otherwise be displayed, the smaller size letters being acceptable since the operator is adjacent to the apparatus 40 and therefore does not require larger sized letters, which are used for the ordinary operations. The larger size letters may be seen, of course, at a greater distance form the apparatus 40, as when the operator is at the vehicle, and following instructions provided by the video screen display dealing with performing functions at the vehicle.

The claims and the specification describe the invention presented, and the terms that are employed in the claims draw their meaning from the use of such terms in the specification. Some terms employed in the prior art may be broader in meaning than specifically employed herein. Whenever there is a question between the broader definition of such term as used in the prior art and the more specific use of the term herein, the more specific meaning is meant.

It will be obvious to those skilled in the art that various changes may be made without departing from the spirit of the invention, and therefore the invention is not limited to that shown in the drawing and described in the specification, but only as indicated in the appended claims.