Externally Controlled Variable Displacement Compressor

The externally controlled variable displacement A/C 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 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.
• Use the oil adding procedure specified for this vehicle when installing a new A/C compressor. Refer to REFRIGERANT OIL ADDING 

The PCM  pulse width modulates the ground signal to the externally controlled variable displacement compressor solenoid to change the displacement of the A/C compressor by changing the swash plate angle based upon the:

• evaporator temperature
• ambient air temperature
• engine Revolutions Per Minute (RPM)
• vehicle speed
• A/C high side pressure
• intake air temperature