Heating and Air Conditioning: Description and Operation

This system provides automatic regulation of vehicle interior temperature regardless of outside temperature changes. The control panel has two push-buttons to adjust the desired temperature up or down and one to request a display of outside temperature. Six additional push-button permit the driver to choose various modes of system operation. A seventh button is incorporated if the vehicle is equipped with a rear window defogger.

During normal operation, fresh air is drawn in from outside the car and routed to the blower. The blower directs the air to the evaporator core where it is filtered, dehumidified and cooled to approximately 35 degrees F. From the evaporator, the air is forced through or around the heater core, depending on temperature requirements. The air mix door controls the actual amount of heating that takes place. The conditioned air exits through the A/C ducts in the instrument panel, the heater ducts at floor level or defroster outlets, depending on operating mode selected.

Five temperature sensors are monitored by the Body Computer Module (BCM) on Deville and Fleetwood models while six temperature sensors are monitored by the BCM on Eldorado and Seville models. These temperature values are sent to the BCM by thermistors to control the Electronic Climate Control.