Auxiliary Heating and A/C Operation

The purpose of the auxiliary heating and A/C system is to supply heat or cool air to the rear interior of the vehicle. The rear A/C system will also remove humidity from the rear of the vehicle. The front HVAC control assembly controls both the auxiliary cooling and heating system temperatures. The heating system sends warm air through floor air ducts. Please check that the rear passenger floor mats are not covering up the floor vent openings this will have an effect on heating performance. The rear overhead vent ducts receive cool air when the front A/C engages. Even it the front A/C system is off air can still be circulated to the rear. The auxiliary system incorporates a coolant bypass valve. The coolant bypass valve solenoid energizes a vacuum valve and allows warm coolant into the rear heater core.