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  #1  
Old 08-25-2005, 10:36 PM
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A/C questions - '85 300D

Car - '85 300D which we have owned for 15 years.

A/C history
- Original compressor failed in May 1998 - System converted to R134a (no choice here) Trumark compressor installed plus rec./drier
- Dec 1999 - Compressor failed - Replaced with remanufactured compressor along with another rec/drier.
- May 2000 A/C not working - evacuated and leak tested - no leaks - recharged. Working again.
- Dec 2000 - Engine replaced (that's another story!) - A/C re-installed and recharged - Slight leak suspected - added dye, but never checked.
- Oct 2002 - A/C drive belt broke - Cause - seized compressor

Since then, we have done without A/C.

After a long hot summer, once again thinking of fixing A/C, but have some questions:

1. Presently, compressor is still on car and seized. There should still be Freon in the system. I would like to check that evaporator & condenser & rest of system is not leaking or in need of replacement - Is there a way for me to do a static pressure or vacuum test without special equipment? How do I do this?

2. When Freon (R134 in this case) leaks from a system, I have heard that some oil goes with it and system can seize due to insufficient oil. When recharging with Freon, as done in 2000, presumably some oil should be added - But how would anyone know how much to add?

After previous experience and a lot of $$ spent, I don't want to spend a lot of $$ only to have it all fail again in a year or so. As I see it, I need:
- No leaks
- Good compressor
- New rec/drier (and perhaps new valve too?)
- Clean system
- Proper amount of R134 and oil.

Any advice, comments, answers, moral support welcomed I want to be cool again
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  #2  
Old 08-25-2005, 10:45 PM
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Thumbs up You answered most of your question...

- No leaks
- Good compressor
- New rec/drier.
- Clean system
- Proper amount of R-12 and oil.

You need a friend in the USA with an R-12 license.

Flushing the system is a PIA, replacing parts is easy.

Converting to R-134A is a BAD idea.
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  #3  
Old 08-25-2005, 11:06 PM
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I had the same issue with the 123 when I owned it. Compressor was replaced and the entire system flushed. Two years later, the compressor goes out again and I need to spend another $800. to get it working again.

In many discussions with Larry Bible on this forum, he indicated that this is not uncommon with vehicles converted to R-134. The significantly higher system pressures and the way the compressor is mounted shortens the life of the compressor dramatically.

The solution is to convert back to R-12. If the compressor operates at significantly lower pressures, odds are that it will last significantly longer.

Sure, the R-12 costs more at the initial fill, but, what does a compressor cost you?
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  #4  
Old 08-25-2005, 11:12 PM
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Quote:
Originally Posted by whunter
- No leaks
- Good compressor
- New rec/drier.
- Clean system
- Proper amount of R-12 and oil.

You need a friend in the USA with an R-12 license.

Flushing the system is a PIA, replacing parts is easy.

Converting to R-134A is a BAD idea.
Unfortunately, in Canada, I think we have to live with R134a. If we changed back to R12, we might have trouble getting unit serviced.
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  #5  
Old 08-26-2005, 09:35 AM
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Perhaps you should look at converting to a compressor brand which lasts longer with 134a.....
Do you have the Delco R-4 as original equipment ?
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  #6  
Old 08-26-2005, 10:48 AM
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Quote:
Originally Posted by leathermang
Perhaps you should look at converting to a compressor brand which lasts longer with 134a.....
Do you have the Delco R-4 as original equipment ?
The compressors used are R-4's, but after the original failed, a Truemark was installed - did not last long, next was a rebuilt MB compressor - don't know what make, also failed.

What type of compressor would last longer with R134a?
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  #7  
Old 08-26-2005, 10:52 AM
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Find a late model which was made to run 134a....
Maybe ask on aircondition.com .....
or call Tray at Carlisle Auto air in San Antonio...
I have never asked that question because I am staying with R12 myself....
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  #8  
Old 08-26-2005, 09:48 PM
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Quote:
Originally Posted by Graham
The compressors used are R-4's, but after the original failed, a Truemark was installed - did not last long, next was a rebuilt MB compressor - don't know what make, also failed.

What type of compressor would last longer with R134a?
I believe that it is generally accepted that you want a brand new compressor for use with R134a. If you are going to get half a chance at a decent lifetime, you need to avoid the rebuilts without any question.
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  #9  
Old 08-26-2005, 10:34 PM
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Quote:
Originally Posted by Brian Carlton
I believe that it is generally accepted that you want a brand new compressor for use with R134a. If you are going to get half a chance at a decent lifetime, you need to avoid the rebuilts without any question.
Any suggestions for a reliable make? - The first Truemark that was installed was a new compressor (Cost ~C$600.00) and even the local distributor admitted it was poor quality (and replaced it with a rebuilt OE compressor at no cost even although warranty was out).

Checked car today - Opened schrader valve - no hiss - presumably almost no Freon left. Tried to rotate compressor - seemed frozen solid.

Doesn't seem like there is way to test evaporator/condenser for leaks without first replacing compressor?
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  #10  
Old 08-27-2005, 12:15 AM
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I've had many remans fail at our shop (ecspecially r-4's ) common on chevy's.
Not sure what can be done about that. We've had them defective right out of the box. Use new when you can.
Haven't had a problem with higher pressures as we only put in 80% R134a that the car would use if using R12 (if in doubt less is better than more). Also it's a good idea to install an inline filter just before the compressor (Any AC shop should have them). Make sure the system is put through it's paces after the repair (No faulty switches allowing pressures to get too high).
Rememder that the AC compessor runs on all but the econo and off positions on your cimate control.
Good luck.

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  #11  
Old 08-27-2005, 01:11 AM
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" Also it's a good idea to install an inline filter just before the compressor "

Larry and I have been saying this for years....and I think I posted a picture of an aftermarket add on type available...

You can get this sort of speciality stuff from Carlisle Auto Air.... I have posted their info before....
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  #12  
Old 08-27-2005, 01:14 AM
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The R-4 Delco , Puck on Steroids, is a scotchyoke design...
most ompressors are radial or swashplate....
they are smoother and require less hp to run them...
so any late model usually installed on new cars using 134a should be stronger.
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  #13  
Old 08-27-2005, 10:38 AM
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Sometimes it's just a crapshoot.

We just put a brand new Delco R4 on my 300D. It went BANG about 30 seconds into the charging process. Took it back and got another one, and all is well (except I'm out a can of R-12 of course).
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  #14  
Old 08-27-2005, 10:55 AM
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Quote:
Originally Posted by leathermang
The R-4 Delco , Puck on Steroids, is a scotchyoke design...
most ompressors are radial or swashplate....
they are smoother and require less hp to run them...
so any late model usually installed on new cars using 134a should be stronger.
Has anyone adapted a late model R134a compressor to a 123 diesel. Must be some mounting modifications required?
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  #15  
Old 08-27-2005, 11:09 AM
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Quote:
Originally Posted by Palangi
Sometimes it's just a crapshoot.

We just put a brand new Delco R4 on my 300D. It went BANG about 30 seconds into the charging process. Took it back and got another one, and all is well (except I'm out a can of R-12 of course).
What does a new Delco R4 cost?

We discussed the drain hole locations some time back (see link below) - Do these new standard Delco R-4's have the oil lube holes in the proper location for under engine installation as required on 123 diesels?

GM & Aftermarket A/C Compressors vs MB compressors
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