When not in operation, the clutch plate rests a specified distance away from the AC pulley to prevent compressor operation. Likewise, the thermal fuse is used to prevent the clutch from engaging when the compressor reaches an unsafe threshold heat level. If it’s clogged, the computer won’t energize the clutch coil. The computer monitors to the flow control valve to ensure proper refrigerant flow. Thermal fuse or flow control valve isn’t working or is blown. The PCM will not provide ground to the clutch relay if those readings are out of spec. In a PCM operated system, check the inputs from the low/high pressure switches or pressure transducer. The relay can’t operate without the ground connection on the control coil. The heater control or PCM isn’t providing ground to the control coil on the AC compressor clutch relay. Remove the electrical connector from the clutch coil and check for good ground using a multimeter. A corroded ground connection will prevent the clutch coil from generating a magnetic field, resulting in a compressor clutch won’t engage situation.
The high pressure switch is located on a high pressure line or right on the receiver/dryer. Starting the AC compressor against high pressure, whether due to an overcharge condition or a restricted component can damage the clutch and compressor. The low pressure switch is installed on the low pressure line or right on the accumulator. That’s why you should NEVER jump across a low pressure switch to force the AC compressor to engage. If the compressor operates with a low refrigerant charge, the system won’t carry enough oil to the compressor, causing it to fail. Low pressure indicates a low refrigerant charge. To test, unplug the electrical connector at the clutch coil and test for battery voltage with the AC turned on.
AC CLUTCH REPAIR FULL
The electrical contacts in the AC clutch relay can develop pitting that prevent full current flow to the clutch coil, resulting in no clutch engagement. That would result in a weak magnetic field that prevents full clutch plate to pulley engagement. If the reading is too low, that’s an indication of a short between coil windings. Finally, attach both leads to the two clutch coil terminals and compare the resistance reading to factory specifications. Then switch to the other clutch coil terminal and check for short to ground. To test for a short to ground, set a multimeter to the ohms scale and touch one lead to a clutch coil terminal and the other to a ground point on the compressor. The most common cause of a blown clutch fuse is a short to ground in the compressor clutch coil. In newer vehicles where the AC is controlled by the heater control head or the PCM, the wiring is quite different. When turned on, power flows through the switch and then to a low and high pressure switch before flowing to the compressor clutch coil. In older non-computerized vehicles power flows from a fuse to the AC switch. How does an AC compressor clutch engage?Ĭarmakers use several different wiring methods to provide power to the clutch coil. When the clutch coil receives power and generates a magnetic field, it pulls a portion of the clutch plate against the clutch body/pulley, causing it to rotate the compressor shaft.
AC CLUTCH REPAIR DRIVER
When the driver requests AC, the system provides power to the clutch coil, thereby generating a magnetic field, which turn the pulley into a strong magnet.
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