PURPOSE: To avoid the conventional problem that a DC-DC converter generates heat, by switching two thermomodules over to parallel connection when a supply voltage is DC 12V and to series connection when the supply voltage is DC 24V and by driving them thereby with DC 12V at all times.

CONSTITUTION: Two thermomodules 1A and 1B having specifications of DC 12V are used and they are connected in parallel when a supply voltage is DC 12V, while they are connected in series when the supply voltage is DC 24V. Thereby DC 12V is always impressed on the thermomodules 1A and 1B. At the time when the inside of a storage is cooled, the potential at a point (c) is positive and, therefore, the supply voltage is supplied to a fan 4 through a diode D2 when it is DC 12V. At the time of heating, on the other hand, the potential at a point (d) is positive and, therefore, the supply voltage is supplied to the fan 4 through a diode D1. Accordingly, this equipment is free entirely from the possibility that a DC-DC converter generates heat, and it is also advantageous in terms of the cost.