General Information

The purpose of the heater is to supply heat to the interior of the vehicle. The vehicle operator can determine the level of heat by turning the temperature switch, located on the HVAC control assembly, to any setting. The temperature switch can change the vehicle's air temperature regardless of the HVAC mode setting, heater, A/C or OFF.

The underhood fuse block provides power to the air temperature actuator through the ignition 3 voltage circuit. Power and ground are provided to the HVAC control assembly by the ignition 3 voltage, battery positive voltage and ground circuits.

When a desired temperature setting is selected, a variable resistor is used to determine the air temperature door control signals value. A resistor inside the HVAC control assembly provides a varying ground to the air temperature actuator through the air temperature door control circuit. This changes the 12-volt signal coming into the actuator and varies the voltage so the actuator is moved into the proper position. The motor opens the air temperature actuator to a position to divert sufficient air past the heater core to achieve the desired vehicle temperature. Ground is provided by the ground circuit.