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AC Compressor Grinding!?

8K views 11 replies 4 participants last post by  roadhog 
#1 ·
So, on a long drive, my friends car went into 'limp' mode, but after pulling over for awhile all seemed ok and she drove home. She thought that the fan was not coming on as when she gets home she can normally hear it. SHE did not notice whether or not the temp gauge went beyond what it should.
I checked coolant etc, that both sides of the radiator was heating up, and all seemed ok. Left the car running but after a good while it wouldn't heat up past the medium level so that the fan would come on. Read on this forum about the fan resistor issues that occur, and deduced that you can at least check that the fan runs on the lower speed by switching on the a/c. On switching on the a/c, I heard a horrible grinding/crunching noise coming from somewhere around the serpent-belt area. On closer inspection it would appear that it's coming from the a/c compressor. Switch the a/c off and no noise and no problems running. It sounds like the a/c compressor bearings have gone. Can the bearing alone be replaced, or is a whole compressor swap needed?
 
#3 ·
Thanks KidneySD, problem around here is that they don't fix anything; always swap for new. For sure they'll want to replace the ac compressor whether or not necessary! Would like to try and keep costs down. Have read quite a bit on here about changing the clutch/coil on these, but the fact that the ac is working, even with the noise, I don't think it's the clutch. Nothing also on here regards the clutch issue creating a grinding noise. I don't think that the coil 'sets' come with the bearings; or am I wrong?
 
#5 ·
Thanks for the heads-up on the clutch kit. A new developement though; I took the wheel and arch-lining off to take a closer look and the serpentine belt was shot to pieces with strips hanging off it. I'm hoping that's it's just the belt, and not one of the pulleys from supercharger, alternator, compressor etc that has caused the belt to disintegrate. Will be fitting a new belt tomorrow (excellent 'to-do's' on here without needing the special tool to release the tensioner, thanks), fire up the car, and hopefully that's that.
 
#7 ·
Ok, so changed the belt, not a hard job with a piece of 1m long flat iron 6mm thick to 'un-tension' the tensioner. All seemed ok, but after a drive of about 25 mins, said driver put on the ac and all hell broke loose again. Car went into limp mode. She drove to nearest garage, had a 5min sit, and started up again minus ac. All ok, except engine light still on. When she got home I went around to have a look, the belt is still fine, all seems ok (obviously didn't try ac as that seems to be the issue). Due to de-gassing etc., I'm not going to try the new ac compressor change myself, but my preferred mechanic is off for two weeks now! Is it ok driving the car with the engine light on? Is it saying something is wrong, or that something wrong happened?
 
#9 ·
Hello roadhog, yep, checked them all and all seemed ok, no grating or grinding, nothing seemed loose. The crankshaft pulley I couldn't turn and don't know how to manually crank the enfine so couldn't really check that. The ac compressor pulley was especially smooth so a bit surprised at that appearing to be the problem!? Maybe the clutch on it is ok, and something else is wrong with the condenser???
 
#10 ·
I'd be surprised if you had managed to turn the crank by hand.
Did you try to turn the A/C compressor itself? I don't mean just the outer pulley (which will free wheel when the clutch is not engaged) but the inner part. You should be able to turn the compressor, I still suspect yours is faulty.
The A/C condenser is just the radiator, no moving parts in there.

I'd whip the belt off again have another look.
 
#11 ·
Thanks for the input Roadhog,

No, I couldn't turn the crank by hand, but I thought there was maybe a way of turning it independently.
I meant compressor, not condensor. I didn't try turn the inner part; truth be told I don't know how the compressor works and didn't even realise that there was an inner part that'd turn. It was just the outer pulley that I was able to turn. How would I turn the inner part? As a new compressor is nigh on €400 over here, I'd like to be sure that that is what's wrong, even if it does look obvious that it is.
One thing I was wondering, could there be something wrong with the alternator, crank, supercharger, that only manifests itself when the compressor is activated adding to the load on the belt?
 
#12 ·
It's possible. Switching the A/C on would add load to the belt and it could be that a different component has a bearing problem which only manifests itself under that load. Remote possibility I'd have thought and shouldn't affect the crank for starters. Does the supercharger have it's own belt? Not familiar with the S sorry. Which leaves the water pump and the alternator but you said you checked them.
Have a look at the attached picture. It's a basic compressor clutch layout, yours will be similar.
The pulley assembly turns with the belt all the time the engine is running. The clutch drive plate is fixed onto the compressor shaft and doesn't turn until the clutch (field coil) is energised. The field coil is an electro magnet, when energised it pulls the drive plate against the pulley and friction causes the drive plate to turn with the pulley. That's what makes your compressor turn.
Therefore, if you can turn the drive plate by hand, at least it will prove that the compressor hasn't seized up. If it doesn't turn, or is rough, the problem lies within the compressor. You can check that without even taking the belt off as long as you can get a hand to the front face of the pulley.

CAUTION: Do the check only with the engine off and the keys firmly in your pocket!
 

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