Blower Motor: Description and Operation

Circuit Description

Blower control
With the ignition switch in ON, battery voltage is applied to the coil of the blower relay. With the blower switch in any position except OFF, ground is provided to the coil of the blower relay through the blower switch. Battery voltage is then applied to the blower motor through the closed contacts of the blower relay, ground is provided to the blower motor through the blower resistor and blower switch for the desired blower motor speed. As the blower switch is moved from OFF to position HI, resistors in the resistor block are bypassed. Decreasing the resistance will increase the voltage applied to the blower motor. This increases the blower motor speed.

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