Ok, I've searched the archives and no one seems to have had my problem yet, so I'm not counting my chickens yet. Here's the story; Early this year I decided to fit AC to my 79 GTB. It was all disconnected and apart when I got the car, but it had all the brackets mounts and the original compressor. I bought a new york compressor, reciever, got a new bearing for the clutch and new bearings for the tensioner. I had it all fitted up and gassed and the on the cooling side of things it works fine. The problem is, there's a resonant vibration that sounds like a rattle that happens when the car is running between 3000 and 3400 rpm. This happens regardless of whether the compressor clutch is engaged or not. I checked the belt alignment. No worries there. I've run the compressor without the tensioner fitted, the noise still happens. With the A/C belt removed the noise disappears. This tells me that the somethings up with the rotating mass. I've disconnected everything again, pulled off the compressor, and the bearing feels fine and rotates smoothly. Now I'm running out of ideas. All I can think of is that when it's all hooked up and rotating there's a vibration being caused somehow through the mounting bracket and the cambelt cover and that when I put it all back together I should use a bunch of rubber washers at all the mounting points to hopefully dampen any vibration. Any Ideas all you mechanical Gurus??? Thanks
Typically the noise you describes is the A/C lines at the compressor rubbing/resonating on the body/fuel tank/etc. Go to home depot and buy some 3/4' hot water pipe insulation "Split Stuff" and wrap the hose as far back towards the front of the car as you can go and zip tie.
Did you install your own freon too? If so, did you use gages? I've seen cars with TOO much freon cause a vibration due to high head pressures. Not saying that's it, as you need to check out the lines from previous reply, but if they are ok, check this out too.
Speeedcore, I didn't use my own freon. I had it done at a shop. Even if it did have too much freon, the noise happens regardless of whether the clucth is engaged or freewheeling. Ferrarimechanic, if it is the pipes rubbing wouldn't the noise happen all the time regardless of whether the A/C belt was fitted or not? As soon as I took the belt off the noise disappeared. The hoses were still connected to the compressor though. What do you think? I'd like to have all my bases covered before I put everthing back together. I'm willing to wrap the pipes in insulataion regardless, sounds like a good idea.
