Compressor HVAC: Description and Operation

A/C Compressor and Clutch Assembly

NOTE: Internal A/C compressor components are not serviced separately. The A/C compressor, minus the A/C compressor clutch and field coil, is serviced as an assembly. A new A/C pressure relief is included with replacement A/C compressors, but the valve is also available as a separate component and can be independently replaced if needed. The A/C compressor clutch, A/C compressor pulley and A/C clutch field coil are serviceable as a separate assembly.

The A/C compressor has the following characteristics:

- A non-serviceable shaft seal.
- The A/C compressor uses PAG Refrigerant Compressor Oil (R-134a Systems) YN-12-D. This oil contains special additives required for the A/C compressor.
- The A/C compressor oil in the A/C system may darken over time while maintaining normal oil viscosity. This is normal for A/C systems because of break-in wear.
- Use the refrigerant oil adding procedure specified for this vehicle when installing a new A/C compressor or any other A/C component.

When battery voltage is applied to the A/C compressor clutch field coil, the clutch disc and hub assembly is drawn toward the A/C clutch pulley. The magnetic force locks the clutch plate and hub assembly and the A/C clutch pulley together as one unit, causing the compressor shaft to rotate with the engine. When battery voltage is removed from the A/C compressor clutch field coil, springs in the clutch plate and hub assembly move the clutch plate away from the A/C clutch pulley.

An A/C clutch diode is included for A/C clutch field coil circuit spike suppression. The A/C clutch diode is located in the Battery Junction Box (BJB).