The A/C on our 2007 Nissan Altima went a year ago. Our trusty mechanic diagnosed the problem and replaced the clutch, which is now past the one-year warranty. The A/C has now became intermittent, and the mechanic’s best assessment is that the recent clutch has also failed, but he has no clue about an underlying cause, if any. His recommendation to get the A/C running again is to replace the clutch again, assuming that it is the source of the problem. He advises that this is the only way to determine if it is in fact the cause or something else highly obscure is behind the clutch failure.
If there is absolutely no doubt that the compressor clutch has failed then the cause can vary.
If the clutch coil has failed electrically then it is likely “just one of those things”.
If the clutch bearing has failed then see above.
If the clutch is slipping and causing screeching, grinding, or what have you that may be due to:
A/C high side pressure chronically too high and stressing the friction surface.
The air gap on the clutch was not checked and adjusted when installed. That can lead to premature failure if the gap is too wide.
There’s also the very faint possibility that refrigerant oil leaking past a compressor shaft seal can contaminate the friction surface and cause slippage which could then lead to failure. Not likely; just pointing out a what-if.
Hope that helps.
Thank you for your helpful information. Since the only symptom I am aware of is the A/C intermittency, I gather it must be the first explanation (one of those things). I am hearing a kind of rhythmic rattling noise, which I have not yet pointed out to our mechanic, but it does not sound like one of those other things.
If this rattling only occurs when the A/C compressor is engaged it’s possible that the compressor could be rattling a bit from low refrigerant oil and this would have nothing to do with the clutch.
It’s normal over time for an aged automobile A/C system to lose some refrigerant and with that loss some refrigerant oil is also lost.
If the above is the case here then it is quite easy to add an ounce or two of oil to the system and which could shut it up.
If the intermittency referred to is the compressor short cycling on and off then that may be due to a slightly lowered refrigerant level. If so, adding some refrigerant and oil would be a good idea and this would also have nothing to do with the clutch replacement.
Without knowing low and high side pressures I can only speculate; a.k.a blind guessing… :-). Hope that helps.
I had a compressor clutch pulley bearing go bad on me in my Ford Exploder. I was told that I could just replace the magnetic clutch, so I got the kit and tried to remove the old one. The front snout of the compressor housing broke off as I tired to remove the bearing. I wound up returning the magnetic clutch kit and had to replace the compressor as a unit, with a new orifice tube and accumulator. That was 2 years ago, and it’s behaved ever since.
For issues like @BustedKnuckles experienced, a mechanic told me he hasn’t done AC clutch replacements for years. He will only replace the whole compressor.
Thank you very much for all the comments and suggestions.
My mechanic found and fixed the problem today. It was a broken bolt that connects the clutch to the compressor, so the connection was not secure. As the car moved, the clutch would move slightly back and forth to the compressor resulting in an intermittent connection and a/c function. He welded them together.
