Nathan08T wrote: Mine, however, makes a thud/grinding noise.. I was told the clutch and/or bearings are about to go bad.
Rhanagar wrote:I hope it hasn't got Freon in it ... should be R134a which is a Hydro Fluoro-Carbon.
The thunk is either low refrigerant or low oil ... Have you had a leak check done on it?
Nathan your problem sounds like the bearing gone in the pulley wheel. If you take the belt off and undo the screw in the middle of the clutch plate you can get a peller onto the front plate and it comes off. Behind that is sometimes a circlip which then needs removing. Then the pulley wheel can be pulled off. The pully wheel is an interferance fit with a bearing in the moddle. When mine started making grinding noises it was the pulley wheel at fault and when I removed it I had loads of ball bearings sat on my driveway along with shredded bearing races. I just dumped the system cpompletely and fitted plain pulley in place of the compressor. You should also have your refrigerant level checked and checked for leaks. New worldwide legislation has just kicked in for refrigeration so it will pay you both to get it looked at.
As an aside if the refrigerant is gone from your system the oil in the compressor cannot get around to lubricate the compressor innards. This will lead to eventual siezing of the unit (much like an engine without oil). I don't have to tell you what would happen if that happened at 65 on the highway.
Front bit of a compressor broken down:
In the first photo you can see the giant magnet still attached to the compressor, then the pulley underneath it with the bearing in the middle. In the second photo I am holding the clutch. The inner and outer rings are held on with the plates going outwards. The magnet energises when the A/C is switched on and pulls the rings onto the pulley. As the pulley is turning with the engine once the clutch is engaged the pulley will then turn the clutch and inturn the compressor.
It is recommended to run your A/C at least once a week for 10 mins to ensure you keep the oil and refrigerant inside the system moving around lubricating everthing to prevent things from siezing.