Compressor HVAC: Description and Operation

NOTE: Internal A/C compressor components are not serviced separately. The A/C scroll compressor is serviced only as an assembly. The A/C clutch, A/C clutch pulley and the A/C clutch field coil are serviceable.

The Ford Variable Scroll A/C compressor (SC90V) has the following characteristics:
- A variable capacity function controlled by a suction pressure sensing device.
- Displacement of 90cc (5.5 cubic inch).
- A fixed and orbiting scroll to provide refrigerant compression.
- A non-serviceable shaft seal.
- The A/C compressor uses PAG Refrigerant Compressor Oil YN-12-C, F7AZ-19589-DA or equivalent meeting Ford specification WSH-M1C231-B. This oil contains special additives necessary for the A/C compressor.

The A/C compressor contains a thermal cutout switch which senses the compressor housing temperature. The switch will disengage the A/C compressor clutch if the housing temperature exceeds 120°C (247°F).

SC90V A/C compressors used on the six and eight cylinder engines are not interchangeable.

Compressor Clutch Components:

The SC90V magnetic A/C clutch has the following characteristics:
- It drives the compressor shaft.
- When battery positive voltage (B+) is applied to the A/C clutch field coil, the clutch disc and hub assembly is drawn toward the A/C clutch pulley.
- The magnetic force locks the clutch disc and hub assembly and the A/C clutch pulley together as one unit, causing the compressor shaft to rotate.
- When B+ is removed from the A/C clutch field coil, springs in the clutch disc and hub assembly move the clutch disc away from the A/C clutch pulley.