A/C Compressor or clutch woes, grinding noise

Post by **burnout8488** » 20 Feb 2012, 15:24

Happens after the car has sat for a long time, perhaps 24 hours.

When I turn the A/C on, the clutch will engage, and I hear an absolutely terrible HOWLING/grinding sound that reverberates throughout the cabin. This causes the engine to bog down, and it lasts about 5 seconds. If I rev the car to 2000-3000, it stays, and continues making the horrific noise.

After the 5 seconds, it goes away entirely and will not come back. The compressor appears to be working, vent temps decrease, and it does not cycle on and off (good thing) and holds 35-40psi while operating. No abnormal sounds come from it at all once the initial grinding subsides. Would a bad compressor make terrible sounds constantly? Perhaps the clutch is somehow slipping and makes this sound? I have shimmed the clutch and the gap is within spec. (tiny)

I've replaced everything but the A/C compressor, but regretfully forgot to put any PAG oil in when replacing the evaporator, orifice tube, and dryer. None drained out of my old dryer, or any of the other parts for that matter, so I assumed that it all resided inside the A/C compressor....which is usually where the bulk of it stays, correct? I have since added 4oz of oil... no change whatsoever in the intensity or duration of the grinding.

Post by **burnout8488** » 21 Feb 2012, 22:25

Bump... possibly serpentine belt tensioner too loose?

tireboy-1 · Post by **tireboy-1** » 23 Feb 2012, 20:09

hmmm... It would take some hands on diagnosis to tell what is going on with your A/C system.
Sorry.

Happens after the car has sat for a long time, perhaps 24 hours.

When I turn the A/C on, the clutch will engage, and I hear an absolutely terrible HOWLING/grinding sound that reverberates throughout the cabin. This causes the engine to bog down, and it lasts about 5 seconds. If I rev the car to 2000-3000, it stays, and continues making the horrific noise.

After the 5 seconds, it goes away entirely and will not come back. The compressor appears to be working, vent temps decrease, and it does not cycle on and off (good thing) and holds 35-40psi while operating. No abnormal sounds come from it at all once the initial grinding subsides. Would a bad compressor make terrible sounds constantly? Perhaps the clutch is somehow slipping and makes this sound? I have shimmed the clutch and the gap is within spec. (tiny)

I've replaced everything but the A/C compressor, but regretfully forgot to put any PAG oil in when replacing the evaporator, orifice tube, and dryer. None drained out of my old dryer, or any of the other parts for that matter, so I assumed that it all resided inside the A/C compressor....which is usually where the bulk of it stays, correct? I have since added 4oz of oil... no change whatsoever in the intensity or duration of the grinding.

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Post by **burnout8488** » 24 Feb 2012, 02:50

I've had the chance to spin the compressor by hand in the morning when it's bone cold. It's smooth. The serpentine tensioner looks a little bit moist where the belt rides, perhaps the belt was affected by a power steering fluid leak I used to have.

I'll tack onto this thread... The vent temp only gets to around 48ºF. Could an aftermarket orifice tube cause poor cooling? I got the one on FCPGroton.... I feel like I should have gone OEM... unless it shouldn't make a difference.