Internally Controlled Variable Displacement Compressor (2.5L engine)

NOTE: Proper Air Conditioning (A/C) system diagnosis on a vehicle's compressor is dependent on correct refrigerant system charge and tested in ambient temperatures above 21.1 °C (70 °F).

Variable displacement compressor internals are similar to fixed displacement compressors. The pistons are placed around an angled plate (swash plate) and are pushed back and forth as the plate rotates. Variable displacement compressors vary the swash plate angle to allow piston displacement to vary from 5% (default) to 100% of full capacity to meet cooling demand.

The internally controlled variable displacement compressor has the following characteristics:

A non-serviceable shaft seal.
A non-serviceable pressure relief valve installed in the rear of the compressor to protect the refrigerant system against excessively high refrigerant pressures.
Uses Motorcraft ® PAG Refrigerant Compressor Oil YN-12-D. This oil contains special additives required for the A/C compressor. The oil may have some slightly dark-colored streaks while maintaining normal oil viscosity. This is normal for this A/C compressor because of break-in wear that can discolor the oil.

The piston displacement of the internally controlled variable displacement compressor is controlled with a bellows actuated control valve located in the compressor rear head. The control valve senses the refrigerant suction and head pressures and regulates the pressure in the crankcase. Swash plate angle is a result of the balance of the crankcase pressure on one side of the pistons and suction and head pressure on the other side. The suction pressure varies with the evaporator core temperature. The valve regulates the amount of refrigerant being discharged by an optimum compressor displacement, resulting in the requested evaporator core temperature of approximately 3 °C (37.4 °F).