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  #1  
Old 09-15-2003, 12:03 AM
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What is the best AC oil to use in R12 to R134 Conversion?

http://mywebpages.comcast.net/snow7ice/BENZ.html

What is the best AC oil to use in R12 to R134 Conversion?

After frying 2 compressors,when one of my hoses went bad with a leak I didnt detect, i am starting to wonder why the compressors went, other than the fact that they were Pep Boys rebuilds.

Even if the freon escaped, the compressors shouldnt have toasted..Even "dead" compressors on Old cars dont fail....

One compressor starting making so many terrible noises and when I investigated, i found the innards catatrosphically failed as if someone had stuck sand or steel shavings in the system...
What is the best AC oil to use in R12 to R134 Conversion?

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Old 09-15-2003, 12:11 AM
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Depends upon what is in there. If you are just converting a working system, 2-4 oz of PAG oil is all you need, as the mineral oil will continue to work fine. It's not dissolved in the freon, but it will end up in the compressor and do it's job. The PAG oil will circulate with the freon and lubricate anything else.

If you have the system apart (as in replacing a compressor) the best thing to do is flush very well and put ester oil in. It works better than the PAG in a clean system, or so I've been told.

The real problem is that you have crud flying around in there from a bad compressor, and it will eat a new one in short order. My friend the german mechanic always puts a suction side filter in the suction hose when he replaces a compressor. It helps, but he still has trouble with rebuilt compressors. They usually fail -- only the ones done in Japan seem to last.

Best bet is a new compressor (cheaper than three rebuilts!) and a very complete flush. Better yet is to replace everything -- condensor, lines, and evaporator. Some suppliers won't honor the warrenty if you don't on new compressors. Needless to say, this raises the cost considerably.....

You shouldn't be able to fry the compressor in a current system from loosing the freon -- the low pressure switch should keep it from running when the charge gets low.

Peter
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Old 09-15-2003, 08:20 AM
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So these compressors failed while using R12 ? You did not mention having flushed after the first failure and prior to the one that dramatically failed.... is that the case.... that you did not flush the system in the process of replacing these compressors ? The more detailed description of the history of this problem you can give the better chance of someone maybe catching what is causing you such grief and expense...
Do you own the Mercedes Air Conditioning paper or cd manual for your car ?
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Old 09-15-2003, 09:04 AM
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I agree with Peter and leathermang. If you have debris in the system, you'll have to do more than just replace the compressor and top off the lubricant. There are a number of things you either must or may have to do.

Break the system down to its individual components and flush the debris and lubricant out of each component (except for the compressor and drier).

Install a filter just before the suction side of the compressor.

Sometimes the condenser simply cannot be properly flushed and may have to be replaced.

The drier must be replaced.

Any short cuts would probably result in a short-lived repair.

I thought the best lubricant for systems converted to HFC 134 is the Texaco HFC 100 synthetic lubricant. The name has changed recently, but the guys at aircondition.com and ackits.com should know what you're talking about when ordering it. I use it for all my a/c work.
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Old 09-15-2003, 11:07 AM
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Quote:
Originally posted by Kestas
Install a filter just before the suction side of the compressor.
Where can you get an appropiate filter?

My car's a/c is just fine on a 134 conversion, but I'm planning a 134 conversion on my truck...and it would be nice to have the filter installed there.

Thanks!
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Old 09-15-2003, 11:13 AM
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Surf through these following sites. If you can't find them there, I don't think you'll find them anywhere.

Carlisle Auto Air

AC Source

Aircondition.com
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Old 09-15-2003, 11:14 AM
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A reliable Mercedes dealer mechanic, who works on 123 series on the side said to not buy any rebuilt for the 123. The R4 rebuilts will fail in 1-2 years. So go with a new compressor AFTER a complete flush and filter installation.

Dave
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Old 09-15-2003, 11:44 AM
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Tim, The carlisle guys are in San Antonio... I was introduced to them by TCane... and got the stuff for my 240 from them... and have called for advice several times... they are great.... ask for Trey...

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