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My compressor on my ‘89 started vibrating at the end of a drive yesterday. Actually from an ‘88 but that’s another story. Did a search and found little information about a solution. Original R12 system. When the ac is on it vibrates so badly that the tensioner swings wildly about 3-4 inches. Off and back to normal. Anyone experience this? Still cooling. Runs true with no apparent bearing slop. Compressor going bad? Weak tensioner? Slipping harmonic balancer? Broken compressor bracket? Can feel the vibration throughout the car. I did take the frisbee off 15 years ago. Still have it.
On (some) 1989s there are two steel strengthening braces that were added in addition to the A/C compressor mount itself. If they are missing, or not bolted up correctly on your car, this could be a contributing factor but I don't think it would cause the issue with the compressor itself, just potentially make it worse. They're circled in this photo which looks down from the top center of the radiator towards the passenger side front of the engine.
It sounds like a compressor issue to me but I'm not there seeing/hearing it. The lack of the frisbee could make the issue more visible since it's a flywheel designed to dampen out vibrations in the belt. But, if these braces are either missing or not bolted on correctly, in my mind that could potentially cause a weakness or vibration fatigue crack in the main aluminum compressor mount. Maybe.
All of the above are good places to look but would like to add to it.
Is the compressor keeping up to the with the pulley, Not Slipping
Have you put gauges on system to make sure not over charged or has something creating a high pressure condition.
Thanks everyone. I will check all my braces again. Pretty sure they are all there but will double check. System is definitely not overcharged as I had gauges on it recently. If anything it’s undercharged. Likely needs a can. I need to inspect the bracket and braces closely. Compressor doesn’t appear to be slipping from clutch.
I had those symptoms, engine shaking, tensioner bouncing against the stop, and only at idle with the a/c on. It was so bad I turned off the a/c at stop lights. My problem was the o2 sensor was failing causing a lean condition that only showed systems at idle with the extra load from the a/c compressor.
I had those symptoms, engine shaking, tensioner bouncing against the stop, and only at idle with the a/c on. It was so bad I turned off the a/c at stop lights. My problem was the o2 sensor was failing causing a lean condition that only showed systems at idle with the extra load from the a/c compressor.
Thanks. I’ll connect my scan tool and check that as well.
On (some) 1989s there are two steel strengthening braces that were added in addition to the A/C compressor mount itself. If they are missing, or not bolted up correctly on your car, this could be a contributing factor but I don't think it would cause the issue with the compressor itself, just potentially make it worse. They're circled in this photo which looks down from the top center of the radiator towards the passenger side front of the engine.
It sounds like a compressor issue to me but I'm not there seeing/hearing it. The lack of the frisbee could make the issue more visible since it's a flywheel designed to dampen out vibrations in the belt. But, if these braces are either missing or not bolted on correctly, in my mind that could potentially cause a weakness or vibration fatigue crack in the main aluminum compressor mount. Maybe.
I had those symptoms, engine shaking, tensioner bouncing against the stop, and only at idle with the a/c on. It was so bad I turned off the a/c at stop lights. My problem was the o2 sensor was failing causing a lean condition that only showed systems at idle with the extra load from the a/c compressor.
This is a real possibility! Not certain yet, however, I just started the car after sitting a week and no vibration. No missing braces or cracked brackets. Makes me think that everything will work fine in open loop until a faulty O2 or other sensor creates a lean condition. I still need to dig out my old scan tool to verify. Just posting an update. Thanks everyone. Will post the remedy as soon as I can confirm.
Solved! I replaced the O2 sensor. Not much if any change. Put the frisbee back on and verified all braces in place. Small improvement. Installed new belt and reproduction tensioner today and all is well. Either stretched belt or weak tensioner spring. Maybe both. Really haven’t driven this car much in 2 years because of this. Ready to drive again.
‘88-‘91 AC Compressor Extreme Vibration
