General Description

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 control, located on the HVAC control module, to any setting. The temperature control can change the vehicle's air temperature regardless of the HVAC mode setting; heater or A/C.

The left instrument panel fuse block provides power to the air temperature actuator through the ignition 3 voltage circuit. Power and ground are provided to the HVAC control module by the ignition 3 voltage and ground circuits.

A 5-volt reference signal is sent out over the 5-volt reference circuit to the air temperature actuator. When a desired temperature setting is selected, a variable resistor is used to determine the air temperature door position signals value. That varied 5-volt reference signal is sent back to the logic circuit inside the HVAC control module on the air temperature door position sensor signal circuit. The HVAC module uses this reference voltage to determine the air temperature actuator position through the air temperature door position signal circuit. The motor opens the air mixture door to a position to divert sufficient air past the heater core to achieve the desired vehicle temperature.