Blower Motor: Description and Operation

Circuit Description

Blower control
When the ignition switch is ON and the blower switch is in any position except OFF the blower relay coil energizes and the blower relay contact closes. Battery voltage is then applied to the blower motor through the closed contacts of the blower relay, and a ground is provided to the blower motor through the blower resistor and blower switch. As the blower switch is moved from OFF to HI, resistance of the resistors (built-in blower resistor) will be decreased and the battery voltage applied to the blower motor will be increased. This will increase the blower motor speed.

When the blower switch is in HI, all the resistors are bypassed and the maximum voltage is now applied to the blower motor so that it runs at the highest speed.