AC Death Rattle Diagnosis

[MichaelF]

My '81 TR7 PI has air conditioning -- which has never worked since I bought the car. This really isn't a problem in the Pacific NW, of course. It would 'kick in' when switched on and blow tepid air of some sort so I basically ignored it.

This AM I heard a light rattle on start up which faded quickly with warm-up. I chalked it up to a sticky valve. But later today the rattle has come back and is definitely in the AC compressor. It sounds like ball bearings blasting around a closed space. Quite loud. Turning the AC on/off in the car makes no difference and it no longer 'kicks in'.

Since I was on the road, I simply cut the AC belt and the noise went away.

I'd like to fix this. Is this simply an exhausted charge in the AC ? Something else?

If there are some sources you can recommend for troubleshooting AC, I'd love to know.

 

[Bugeye58]

Mike, it sounds suspiciously like catastrophic compressor failure. It could be for a variety of reasons, running with low refrigerant, a low compressor oil level, or just plain fatigue.
Try turning the compressor by hand and see what it feels like. You'll have to engage the clutch to spin the compressor, or make sure that you're not just free-wheeling the clutch. If it has failed internally, you will immediately be able to tell by the feel.
Sounds like ball bearings being dropped into a blender are never a good sign.
It <u>could</u> just be the clutch, but they usually don't make those kinds of noises when they fail.
If it is the compressor, and you decide to replace it, the entire system will have to be evacuated and flushed, to insure that any bits left in the system are removed, or the new compressor won't last long.
I hate to be the bearer of possibly bad news, but that's what it sounds like to me.
Jeff

 

[Dave Russell]

[ QUOTE ]
It sounds like ball bearings blasting around a closed space. Quite loud. Turning the AC on/off in the car makes no difference and it no longer 'kicks in'.

[/ QUOTE ]
It likely is ball bearings. The compressor has a magnetic clutch. The clutch outer rim runs at all times on it's ball bearings. When the AC is turned on, the outer freewheeling pulley is magnetically coupled to the clutch inner hub to drive the compressor. The clutch can be replaced separately from the compressor if the compressor is still good. Just leave the belt off until you are prepared for some serious AC repair.
D