1975 corvette a/c compressor clutch

[Timothy B.]

I am working on a very low mileage 75 Corvette and when starting the engine cold there is a squeak coming from the A/C compressor which stops as the engine warms. The noise is definitely from the compressor, with the belt removed all quiet.

When the clutch is disengaged or engaged the squeak is present. Could this be the pulley bearing on the front clutch and can just the bearing be replaced.

Also, what is involved to change this system over to the 134, nothing has been touched on this car and the R12 is low because you need to bypass the pressure switch to bring the clutch in.

Any advice is appreciated, my thinking is to replace the front bearing and replace o rings then vacuum and check for leaks.

TIA, Tim

[Joe L.]

Re: 1975 corvette a/c compressor clutch

I am working on a very low mileage 75 Corvette and when starting the engine cold there is a squeak coming from the A/C compressor which stops as the engine warms. The noise is definitely from the compressor, with the belt removed all quiet.

When the clutch is disengaged or engaged the squeak is present. Could this be the pulley bearing on the front clutch and can just the bearing be replaced.

Also, what is involved to change this system over to the 134, nothing has been touched on this car and the R12 is low because you need to bypass the pressure switch to bring the clutch in.

Any advice is appreciated, my thinking is to replace the front bearing and replace o rings then vacuum and check for leaks.

TIA, Tim

Tim------


I suppose the noise could be caused by the pulley bearing. However, it's also possible that it's just a squeaking belt. Have you tried a new belt?

In any event, the pulley bearing can be replaced. The bearing was GM #6557684, but it's discontinued. No problem, a bearing is available from Federal-Mogul/National under their number 907257. About 25 bucks.

I would not recommend converting this car to R-134a. R-12 is readily available. Even though it's no longer manufactured, pretty soon, I expect that supply is going to far exceed demand since there are so few cars around that require it anymore. The last cars that used it were made in the mid-90's, about 25 years ago.

[Larry M.]

Re: 1975 corvette a/c compressor clutch

The front clutch bearing can be replaced without discharging the refrigerant. Did this on my 1978 Z/28 with the A6 compressor.

You may need a few tools/pullers to do the job correctly. They are not expensive.

Larry

[Terry M.]

Re: 1975 corvette a/c compressor clutch

I am working on a very low mileage 75 Corvette and when starting the engine cold there is a squeak coming from the A/C compressor which stops as the engine warms. The noise is definitely from the compressor, with the belt removed all quiet.

When the clutch is disengaged or engaged the squeak is present. Could this be the pulley bearing on the front clutch and can just the bearing be replaced.

Also, what is involved to change this system over to the 134, nothing has been touched on this car and the R12 is low because you need to bypass the pressure switch to bring the clutch in.

Any advice is appreciated, my thinking is to replace the front bearing and replace o rings then vacuum and check for leaks.

TIA, Tim

With the compressor clutch engaged the front bearing doesn't spin (actually the whole bearing spins together and there is no relative movement between the inner and outer race). Thus if the noise is present both with the clutch engaged and not engaged it is unlikely the front bearing is the source of the noise.
The suggestion to look to the belt is a good one. If coolant has ever been spilled on the belt or pulleys the belt can squeak for a long time or until both belt and pulleys are thoroughly cleaned. If a light spray of water on the pulley while it is turning eliminates the sound, you have noise form the belt. Clean the pulleys very well and replace the belt.

[Timothy B.]

Re: 1975 corvette a/c compressor clutch

Thanks everyone, the belt is where I will go next, I appreciate all the suggestions.

[Joe L.]

Re: 1975 corvette a/c compressor clutch

Thanks everyone, the belt is where I will go next, I appreciate all the suggestions.

Timothy------


Two things regarding the belt:

If it's an original belt, it's likely hardened by now. That can cause squeaking;

If there is any rust in the pulleys, particles of rust can embed in the belt and cause squeaking. There's no way of removing the rust particles in this case. Make sure the pulleys are completely free of rust before installing a new belt.