The air temperature description and operation is divided into 3 areas:

HVAC Control Assembly

The HVAC control assembly receives power from the ignition 3 voltage circuit. The HVAC control assembly incorporates three potentiometers to control mode, blower motor, and air temperature settings. The HVAC control assembly does not support personalization or class 2 communications, the assembly is not programmable.

Air Temperature Actuator

The air temperature actuator is a 3 wire bi-directional permanent magnet electric motor. The power ground and control circuits enables the actuator to operate. The HVAC control assembly controls the actuator by a variable 12 volt DC signal.

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 air temperature switch, located on the HVAC control assembly, to any setting. The temperature control can change the vehicle's air temperature regardless of the HVAC mode setting, heater OFF.

When a desired temperature setting is selected, a variable resistor is used to determine the air temperature actuator position signals value. When the air temperature switch is in the warmest position the signal circuit voltage is near 12 volts. The air temperature actuator opens the air temperature door to a position to divert sufficient air past the heater core to achieve the desired vehicle temperature.

Engine coolant is the key element of the heating system. The normal engine operating coolant temperature is controlled by the thermostat. The thermostat also creates a restriction for the cooling system that promotes a positive coolant flow and helps prevent cavitation.

Coolant enters the heater core through the inlet heater hose, in a pressurized state. The heater core is located inside the HVAC module. The heat of the coolant flowing through the heater core is absorbed by the ambient air drawn through the HVAC module. Heated air is distributed to the passenger compartment, through the HVAC module, for passenger comfort. The amount of heat delivered to the passenger compartment is controlled by opening or closing the HVAC module temperature door. The coolant exits the heater core through the return heater hose and recirculated back through the engine cooling system.