Heater Mode

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 console junction block provides power to the left air temperature actuator through the ignition 3 voltage circuit and splice pack. Power and ground are provided to the HVAC control module by the ignition 3 voltage and ground circuits.

When a desired temperature setting is selected, a variable resistor is used to determine the temperature door position signals value. The resistor changes the 12-volt signal coming into the actuator and varies the voltage to move the actuator into the proper position, based on the signal from the HVAC control module. The motor opens the left 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. When the mode actuator sees an open in the control circuit, the actuator defaults to 6 volts and positions the air temperature door to the mid-range.