hi guys

Got back from Carlisle last night. Great show for all of those that couldn't make it but a bit wet on Senday.....

Anyway, brought the '78 back home as it didn't sell which is making the wife very happy. About a 100 miles trip home which is the longest drive the car has seen in YEARS. She ran good I'm glad to say except one thing.
With the A/C on it makes a very noticeable "rattling" noise. Switch off the A/C and it goes away, switch it back on it immediatly comes back. Very annoying!
I had the A/C system completely gone over after I got the car running again in the spring and he replaced the drier/accumulator, replaced all the O Rings, vacuum pressure tested it, and refilled it with freon. It blows nice and cold and works great, almost too cold, but this rattling noise is driving me crazy.
Any ideas??
A friend suggested it might be the bearings on the A/C compressor??

 

is it the original compressor? i didn't see compressor in your list of things gone over above. could very well be bearings or maybe something is just loose.

 

yep, it's the original compressor.
As far as I know he didn't do anything to it while he worked on the system so it's as I bought the car

 

could be the belt rattling against the beltgaurd or something else under there, since it follows the compressor and not the fan

 

The R4 brackets & belt need to be tight- the belt tighter than some other compressors.
New from Chevy R4s are good. (Rebuilt ones can make noise.)

 

Got my belt at 1/4" deflection...not sure that is tight enough..but get very little "rattle"....if at all...(78 original comp)

Rich

 

Check this first, especially if more noticable at idle.

 

 

First 100% determine if the noise is there when the clutch is engaged.
As already suggested, do a visual check of the parts and touch items to find the noise. Just be careful.
If you think it is the compressor, use as stethoscope or even a tube, pipe etc on the compressor to your ear to confirm.
If you confirm it is the compressor itself then have the pressures checked. Incorrect refrigerant levels or oil levels can cause a noise. Only way to check oil level is to evacuate flush and refill.
If bearings were suspect, the system probably would not hold a charge very long. Usually they are piston/valve noises showing to much pressure/wear, but with your mileage wear shouldn't be an issue.

Hopefully if the system was empty and exposed, the ports were sealed off.

 

thanks guys, I'll check the best tightness. hopefully it will be as simple as that although with my luck.............

noonie, the system had been wide open for weeks but the guy that redid the AC for me knew this when he worked on it so I assume he did everything needed to compensate for that.

 

Even the tinest bit of moisture is the systems worst enemy. A/C oil attracts moisture and turns it into an acid, so it is always best to cap off any openings as best as possible, especially the compressor.

That is why it is recommended that a new drier/receiver should be installed every time the system is opened. Then a deep, deep vacuum should be run, to boil out any internal moisture.

Hopefully this is not your situation, but a protected compressor will last longer than one that wasn't.

 

Barry, I can't offer any advice on the A/C, but I did stop and look at the car Friday. No one was around, but it is as nice as the pictures you have posted make it out to be. I hope it works out that you're able to keep it.

 

I've been considering a Sanden when my stock unit goes south...hear there is a big difference in efficiency and head pressures it can take...not mention the oil reservoir...
Rich

 

The old A6 has a reservoir too and is only slightly worse than the sanden, same basic design. The Sanden is nice because of the size and weight.

 

Noonie
I do know he did replace the drier/accumulator (?), replaced the O rings, than vacuum tested the system before refilling it with R12. Not sure what else he did or didn't do but I know he did that much as least.

 

C3 4ME
sorry I missed you. I was just busy constantly running between the '78 in the car corral, the '65 in the '63-'67 registry parking area, and visiting my wife at her booth in the Women's Oasis tent.

 

Hey Barry, I looked for you and the car but didn't find either of you. It was getting late on Friday and pretty hot, and I forgot your space number, and the wife wanted to get going and well you get the picture.

Sorry it didn't sell...did you get any interest? You know you might get a call from someone who saw it and needed some time to think about it. I know that happened to me once.

I guess either way you win or should I say your wife wins.

 

Barry
Report back after you have shecked under the hood and go from there.

 

gq, I understand. sorry we missed each other.
On Friday it was so HOT that I left the show at 4 to go back to the hotel, just couldn't take it anymore.
Not, no real interest at all. A number of people came by, saw the car and commented how nice it looked and were amazed at the low milage, but nothing about interest to purchase.
looking around a saw a lot of rubber bumper cars still there at the end of the show Sun. Seems all C3 interest in the car corral was the chrome bumber cars (no surprise there!).

We found a fellow local vette club member that was hanging out until the end of the show also so his wife was able to help us out and drive the car back home for us (we had 3 cars but only the wife and I to drive them home). Since it didn't sell I wasn't concerned any longer about flatbedding it to "save" the mileage like I did to get it to the show.

The good news is that on the way home the car ran great (I was told) and NO PROBLEMS with it at all. I was a bit concerned since this 100 mile trip was BY FAR the longest drive the car had been on in YEARS AND YEARS - probably since at least 1997, not to mention since I had so much of it apart and than put back together again.
Made a nice test drive and she seems to have passed.

 

will do, thanks!