Blower Speed Control Power Transistor

BLOWER SPEED CONTROL POWER TRANSISTOR

The base voltage of the power transistor changes according to blower drive signals from the ECM. The blower speed changes steplessly in accordance with the change in the power transistor's base voltage.
Should an over-current occur, the thermal fuse connected to the circuit (rated to blow at 144 °C (291 °F)) cuts off the current to the blower.