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Old 01-17-2007, 06:41 PM
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72 A/C Unit

Not sure this is where this belongs.

I have a 72 Chevy A/C truck. When I bought it, it needed a charge so I added some R134. It worked fine.

I later added some high Edlebrock valve covers and had to rotate the compressor. Since then it seems like the it is sticking and not allowing it to spin without making a loud squealing noise. If I rev it up pretty high it goes away. I thought I might have pinched a line so I made some adjustments to take some of the bend out of it. It kind of worked but I still have a problem with the unit stopping. If I drain the system it turns fine.

Could it be the R134 instead of the old freon?

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Old 01-17-2007, 07:05 PM
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I don't see why the R134 would cause the problem, since it worked before you made the changes. Is this a stock A6 compressor, or something smaller? The A6 is heavy and you need to have all the brackets mounted to support the weight.

The first simple fix is to buy a new belt. Belts take a "set" based on the direction they turn. If you switched the belt around when you moved the compressor, it may slip or break when you tighten it back up again and put it under load.

The other possibility is the lineup of the pulleys. You said you had to "rotate" the compressor, so I'm not sure exactly what you moved.

Bruce
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Old 01-17-2007, 08:27 PM
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R134 and R12 do not mix. My guess is you have trashed the compressor.

Vince
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Old 01-17-2007, 11:57 PM
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A/c

r-12 nd 134a don't mix! Their oils are not mixable.72 chev system has and exp. valve and a suction valve.The a6 will work with 134a but r-12 is better.There is an replacement suction valve that serves to cycle the comp. ,like later systems,this valve is 'gutted'.Looks the same,bolts in. If using r134 try to get later HI - Eff .condensor.Best to upgrade to CLUTCH CYCLE ORIFCE TUBE SYSTEM,much simpler.I know this becuse I worked a/c for years.
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Old 01-18-2007, 07:54 AM
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To have added R134 he would have to have put on the fitting adapters. Surely no one would add R134 to an R12 system without the proper flushing and so forth, would they?
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Old 01-18-2007, 08:50 AM
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Nothing was realigned when I rotated the compressor. I also had to get a longer belt to make it work so that is new. I flushed the system out and added the R134a. I also added some additional oil. If there was some R12 left in the system what would cause the compressor to freeze up? No pun intended. I did add the proper fitting to add the R134a. Is there something I could use to try to flush the system with out using more R134a?
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Old 01-18-2007, 09:46 AM
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Quote:
Originally Posted by Mertz
Nothing was realigned when I rotated the compressor. I also had to get a longer belt to make it work so that is new. I flushed the system out and added the R134a. I also added some additional oil. If there was some R12 left in the system what would cause the compressor to freeze up? No pun intended. I did add the proper fitting to add the R134a. Is there something I could use to try to flush the system with out using more R134a?
134 and 12 require a different type of oil. If you flushed and used the proper 134 oil, I would suggest that the compressor has finally just worn out. If you did NOT use 134 oil, the compressor is trashed anyway.

Be sure to flush and install an inline filter when replacing the compressor, as well as upgrades necessary to 134 operation.

I have used Freeze-12, a supposed "drop in replacement" for 12, and had 100% failure rate in 6,000 miles on several vehicles.

Duracool is an approved coolant that cools better than 134 without the high head pressures, and is guaranteed in writing against compressor failure.

Last edited by xntrik; 01-18-2007 at 09:52 AM.
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Old 01-18-2007, 04:05 PM
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Quote:
Originally Posted by pasadenahotrod
To have added R134 he would have to have put on the fitting adapters. Surely no one would add R134 to an R12 system without the proper flushing and so forth, would they?
Only 20 or 30 million people.
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