5. Slipping the Clutch of the AC Compressor
The AC compressor clutch is an electromagnetic device that engages and disengages the air conditioning compressor.
The clutch plate is designed to fit snugly with the compressor pulley. If the clutch of the AC compressor slips, it will cause the car’s AC compressor to cycle on and off every few seconds.
How to spot it?
There are the following causes of a slipping clutch of the AC compressor:
- High discharge pressure
- Lack of compressor lubrication
- Oil on compressor clutch plate
- Loose serpentine belt
- Increased gap between clutch plate and compressor pulley
Your car AC compressor relies on a certain amount of pressure to keep things running smoothly.
When that pressure is exceeded, it can cause the compressor clutch to slip. This is because the compressor has to work hard to push the refrigerant and the magnetic clutch coil does not have enough magnetic force to keep the clutch plate engaged with the compressor pulley.
Similarly, if the compressor does not have proper lubrication, it will overheat and have increased friction between its components. As a result, it will also cause the compressor clutch to slip and disengage the compressor.
Moreover, if there is oil on the compressor clutch plate, the magnetic force from the clutch coil will not properly exert on the clutch plate.
The clutch plate is made of steel that is attracted to the compressor pulley under the action of magnetic force from the clutch coil. So, you need to make sure that the clutch plate of the compressor is oil and dirt-free.
If the air gap between the friction plate of the clutch and the pulley is increased, the magnetic field will not be strong enough to pull and tightly hold the plate against the pulley. As a result, the AC clutch will slip and cause short cycling of the compressor.
To check the clearance between the compressor pulley and the friction plate of the clutch, you can use a feeler gauge.
Make sure to check the gap when the engine is not warm. The nominal air gap settings between the pulley and friction plate can vary between 0.3 mm to 0.8 mm.
If the air gap is greater than 1.0mm, you need to change the clutch assembly. When you remove a clutch plate, you will see a shim (a small metal disc).
The shim sets the desired gap between the pulley and friction plate. You can adjust the air gap with a shim of different thicknesses.