PURPOSE: To make it possible to control the temperature and humidity in a room to the levels pleasant to a human body by a simple structure by a method wherein the operating conditions of a blower and a compressor with respect to the room temperature are controlled sequentially.

CONSTITUTION: An initial OFF point T1OFF is taken at a point lower than the room temperature by an allowable temperature width Tc for a forced compressor operation, a temperature ΔT is taken at a point higher than the OFF point so as to make that point an initial ON point T1ON and a cooling operation is performed with the blow of the maximum air quantity by an indoor blower during the time in which the room temperature TR drops down to T1OFF. The above-mentioned temperature width Tc can be an index of load and therefore, when the room temperature TR after a lapse of a time ts is lower than T1ON, the next operation time is determined to be t1 and when higher, the next operation time is corrected to t1+ Δt. Then when the compressor has run into an ordinary operation condition and the room temperature TR has reached the T1OFF point before the time t1 lapses, the operation of the compressor is stopped and the next operation time t2 is determined to be t1-Δt but when the room temperature TR is still higher than T1OFF after a lapse of the time t1, the operation of the compressor is stopped and the next operation time t2 is determined to be t2=t1. Thus the same process is repeated and when the number of revolutions of the compressor comes to a predetermined value N, the above-mentioned ON point is made equal to the room temperature TR in the initial stage and the above-mentioned OFF point is taken at a point lower than the ON point by ΔT so that the operation and stoppage of the compressor are performed in a repetitive fashion.