Air Conditioning: Notes

WARNING: This page is about a different car, the 2006 Mercury Montego, 2006 Ford Freestyle, and 2006 Ford Five Hundred. However, it is still accessible from the selected car via links, so may be relevant.

The climate control system components include the following:

A/C compressor
A/C clutch assembly
A/C condenser core
A/C evaporator core
Receiver/drier
Connecting refrigerant lines
Thermostatic expansion valve

The refrigerant system incorporates an A/C compressor controlled by the powertrain control module (PCM) through an A/C clutch relay. The climate control assembly sends an A/C request signal to the instrument cluster module which relays the request to the PCM. An evaporator discharge air temperature sensor is used to disengage the A/C compressor clutch when the evaporator core temperature falls below 4°C (39°F).

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 PCM via the instrument cluster module (ICM).
The evaporator discharge air temperature sensor is reading a temperature above 4°C (39°F).
The A/C pressure transducer is not reading a pressure above 2,841 kpa (412 psi) in the high side of the refrigerant system.
The A/C compressor relay is switched to the CLOSED position 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 pressure relief valve is installed in the A/C manifold and tube to protect the refrigerant system against excessively high refrigerant pressures.

Refrigerant flow into the evaporator core is metered by a thermostatic expansion valve (TXV).