Patent ID: 8384334

Claim:
A control unit for controlling driving of a motor that revolves and drives a heat exchanger cooling fan of a cooling system using a cooling medium and a heat exchanger, the control unit including at least a switching element for controlling the driving of the motor, and a controller for transmitting a control signal to the switching element, the control unit comprising: a normal-condition-OFF-type protection element having a first terminal connected to one of two wires connected respectively to a positive and a negative pole connected to the motor, and a second terminal directly connected to a ground wire without being connected to the other of the wires connected to the positive and the negative poles; and short-circuit means, arranged inside the normal-condition-OFF-type protection element, for short-circuiting the first terminal and the second terminal when an overheating caused by the switching element attains a predetermined temperature or higher, wherein the short-circuit means short-circuits the first terminal and the second terminal when the overheating caused by the switching element attains the predetermined temperature or higher, whereby an electric current flowing into the switching element is decreased, and the control unit is shifted to a temperature range safe from the overheating caused by the switching element without stopping the cooling system.