Externally Controlled Variable Displacement A/C Compressor

The externally controlled variable displacement compressor has:

• 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.
• a non serviceable A/C  clutch and field coil.
• Uses Polyalkylene Glycol (PAG) oil or equivalent. 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.

Variable displacement compressors have a swash plate that rotates to reciprocate pistons, which compresses refrigerant. Variable displacement compressors change the swash plate angle to change the refrigerant displacement. The externally controlled variable displacement compressor changes the swash plate angle in accordance with an electrical signal from the PCM  . Externally controlled variable displacement compressor manages displacement by controlling refrigerant differential pressure before and after a throttle at the discharge side; achieving precise cooling capability control in accordance with cabin environment and driving conditions.

The PCM  sends a PWM  signal to the solenoid in the compressor to control the compressor displacement based upon the:

• Evaporator temperature
• Ambient air temperature
• Engine Revolutions Per Minute (RPM)
• Vehicle speed
• A/C  high side pressure
• Intake air temperature