Compressor HVAC: Description and Operation

SC 115 Compressor Clutch:

NOTE:
^ Internal A/C compressor components are not serviced separately. The SC115 A/C compressor is serviced only as an assembly. The clutch plate, the clutch pulley and bearing, and the clutch field coil are serviceable.
^ Installation of a new suction accumulator is not required when repairing the air conditioning system except when there is physical evidence of system contamination from a failed A/C compressor or damage to the suction accumulator.

The SC115 A/C compressor has the following characteristics:
^ Tangential mount design - three lugs.
^ The single manifold block of the compressor manifold and tube assembly fits to the suction and discharge ports. Two O-ring seals are used for sealing.
^ An eccentric bushing is driven by the shaft of the A/C compressor.
^ An orbiting scroll driven by the eccentric bushing compresses the refrigerant gas against the walls of the fixed scroll.
^ Single reed-type discharge valve mounted on the back of the fixed scroll. There are no suction valves.
^ Non-serviceable shaft seal fully supported on both sides by bearings.
^ The A/C compressor uses PAG oil or equivalent. This oil contains special additives required for the A/C compressor.
^ The A/C compressor oil from vehicles equipped with an SC115 A/C compressor may have some slightly dark colored streaks while maintaining a normal oil viscosity. This is normal for this A/C compressor because of break-in wear of the scroll seals that can discolor the oil.
^ Use standard oil matching procedures when replacing compressors.

The magnetic A/C clutch has the following characteristics:
^ It drives the compressor shaft.
^ When battery voltage is applied to the A/C compressor clutch field coil, the clutch plate and hub assembly is drawn toward the clutch pulley.
^ The magnetic force locks the clutch plate and hub assembly and the clutch pulley together as one unit, causing the compressor shaft to rotate.
^ 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 clutch pulley.