Compressor Clutch: Description and Operation
CLUTCH-A/C COMPRESSORDESCRIPTION
NOTE: Typical A/C clutch assembly shown.
The A/C compressor clutch assembly consists of a stationary electromagnetic A/C clutch field coil (4), pulley bearing and pulley assembly (3), clutch plate (2) and shims (7). These components provide the means to engage and disengage the A/C compressor from the engine accessory drive belt.
The A/C clutch field coil and the pulley bearing and pulley assembly are both retained on the nose of the A/C compressor with snap rings (5 and 6). The clutch plate is splined to the compressor shaft and secured with a bolt (1).
OPERATION
The A/C compressor clutch components provide the means to engage and disengage the A/C compressor from the engine accessory drive belt. When the electromagnetic A/C clutch field coil is energized, it magnetically draws the clutch plate into contact with the clutch pulley and drives the compressor shaft. When the coil is not energized, the pulley freewheels on the clutch hub bearing, which is part of the pulley assembly.
A/C compressor clutch engagement is controlled by the powertrain control module (PCM) or the engine control module (ECM), depending on engine application. When the A/C switch is pressed to the On position, the switch sends a request signal on a dedicated hard-wired circuit to the cabin compartment node (CCN), which sends a message on the CAN-B Bus to the totally integrated power module (TIPM), which then transfers the request on the CAN-C Bus to the PCM/ECM, which determines if operating conditions are correct for A/C clutch engagement. When all operating conditions have been met, the PCM/ECM sends a signal on a dedicated hard-wired circuit back to the totally integrated power module (TIPM) to energize the internal A/C clutch high side driver. When energized, the A/C clutch high side driver provides battery current to the A/C clutch field coil. On models equipped with the 1.6L engine, a gateway module is used by the TIPM to communicate to the PCM on the CAN-C Bus.
The A/C clutch control system is diagnosed using a scan tool.
The A/C compressor clutch components cannot be repaired and, if faulty or damaged, they must be replaced.