Air Conditioning (A/C) System

Description

The A/C system uses the principals of thermodynamics to cool the passenger compartment of the vehicle. Using engine power, the compressor compresses gaseous refrigerant into high temperature/high pressure gas. It then pumps this gas into a condenser unit built onto the vehicle's radiator. The condenser cools the gas, changing it into high pressure, low temperature liquid refrigerant. The liquid then goes to the receiver/drier, which first removes any liquid water and then sends the liquid to an evaporator in the heater unit inside the passenger compartment. The evaporator then uses the passenger compartment temperature to turn the liquid back into a gas, extracting heat from the passenger compartment. The gas is then sent back to the compressor, and the cycle begins again.

Operation
With the ignition switch in ON, battery voltage through the WIPER fuse is applied to the coil of the [1][2]A/C relay and to the A/C switch. With the A/C switch ON and the blower switch in any position except OFF, a ground signal is sent through the normally closed contacts of the A/C thermostat to the PCM A/C request input at terminal C248/6. Ground is also provided to the A/C ON indicator in the A/C switch.

Operating parameters permitting, the PCM will ground the coil of the [1][2]A/C relay at PCM terminal C248/4. The A/C relay energizes and applies battery voltage through the closed contacts of the relay and the normally closed contacts of the A/C dual pressure switch to the A/C compressor clutch. The clutch engages and the vehicle interior begins to cool.