Auxiliary Heating and A/C Operation

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There are two separate control assemblies for the auxiliary HVAC system. There is the front auxiliary HVAC control assembly and the rear auxiliary HVAC control assembly. Both control assemblies provide input to the auxiliary HVAC control processor. If the front auxiliary HVAC control assembly is in any other position than OFF or AUX, the auxiliary HVAC control processor will only use inputs from the front HVAC controls. If the front auxiliary HVAC control assembly is in the AUX position, then the system will only function with inputs from the rear auxiliary HVAC control assembly. If the front auxiliary HVAC control assembly is in the OFF position, then the auxiliary HVAC control processor does not respond to input from either control assembly. The auxiliary HVAC control processor can not request A/C compressor clutch engagement from the PCM.

The auxiliary air temperature switch is a rotary knob switch. Turning the air temperature switch to the warmest position diverts most of the airflow through the heater core, which increases the outlet air temperature. Turning the air temperature switch to the coolest position diverts most of the airflow around the heater core, which decreases the outlet air temperature.