HVAC System - Manual: Operation: Notes

The system uses a reheat method to provide conditioned air to the passenger compartment. All airflow from the blower motor passes through the evaporator core. The system regulates the temperature by reheating a portion of the air and blending it with the remaining cool air to the desired temperature. The temperature blending is varied by the air temperature control door, which regulates the amount of air that flows through and around the heater core, where it is then mixed and distributed.

The air distribution system is designed to provide air flow from the defroster nozzle when no vacuum is applied to any of the vacuum control motors. This is done to make sure defrost is available in the event of a system vacuum leak.

Passenger compartment air is exhausted from the vehicle through open windows or luggage compartment air vents.

The A/C compressor is controlled by a clutch cycling pressure switch. See Figure. Clutch cycling pressure switch is connected in series with compressor clutch. Clutch cycling pressure switch is used to prevent evaporator core icing during normal system operation. Compressor will operate if ambient temperature is greater than 43°F (6°C) and mode selector is in any position except VENT and FLOOR. A pressure relief valve is installed in A/C manifold and tube assembly to protect A/C system against excessively high refrigerant pressures.