Air Conditioning: Notes

WARNING: This page is about a different car, the 2007 Lincoln Mark LT and 2007 Ford Pickup. However, it is still accessible from the selected car via links, so may be relevant.

The A/C refrigerant system is a clutch cycling orifice tube type. The system components are the following:

A/C compressor
A/C condenser core
A/C evaporator core
Suction accumulator
Connecting refrigerant lines

The refrigeration system operation is controlled by the following:

Evaporator core orifice tube
A/C cycling switch
A/C compressor pressure relief valve
A/C pressure transducer

The refrigerant system incorporates an A/C compressor controlled by the powertrain control module (PCM) through an A/C clutch relay.

The A/C cycling switch senses evaporator core pressure to control A/C compressor operation.

An evaporator core orifice tube is installed in the condenser-to-evaporator line at the A/C condenser fitting to meter the liquid refrigerant into the evaporator core.

The A/C compressor clutch will only be engaged by the PCM if all of the following conditions are met:

The climate control assembly is set to a mode which provides an A/C request to the instrument cluster. This request is then transferred to the PCM through the CAN bus.
The A/C cycling switch is reading an acceptable low side refrigerant pressure.
The A/C pressure transducer is reading an acceptable high side refrigerant pressure.
The A/C compressor relay is energized by the PCM.
The engine coolant temperature is not excessively high.
The PCM has not detected a wide open throttle (WOT) condition.

An A/C compressor pressure relief valve is installed in the compressor manifold and tube assembly to protect the refrigerant system against excessively high refrigerant pressures.