HVAC Blower Controls Circuit Description

The blower motor circuit contains the following components:
^ The blower motor
^ The blower resistor assembly
^ The blower motor relay
^ The heater
- The A/C and rear defogger control assembly
- The blower switch
- The mode selector

Battery voltage applies to the mode selector when the ignition switch is in RUN. The mode selector energizes the blower motor relay when you make any selection except OFF. The blower motor relay sends battery voltage to the blower motor. The blower motor ground controls the speed of the blower motor. When the blower switch is set to 1, the blower resistor limits the voltage to the blower motor. The resistor slows the motor down. When the blower switch is set to 2 or 3, the resistance decreases in order to allow more voltage to the blower motor. When the blower switch is set to 4 the following events occur:
^ The blower switch bypasses the blower resistor.
^ The blower switch allows full battery voltage at the blower motor.

Then, the blower runs at high speed.