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  #1  
Old 06-11-2007, 04:44 PM
slk230red's Avatar
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Compressor Seized, go to R134a or keep R12?

Well, the original compressor on my '93 190E 2.3 seized yesterday, so I'll either have to buy a new car or replace the compressor, drier, vacuum the system and refill with R12.
Before I buy a new compressor and drier, has anyone replaced a 190E 2.3 compressor lately? Any problems, and/or have you switched over to R134a?

Thanks in advance,

Dave

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  #2  
Old 06-11-2007, 05:22 PM
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My $.02 - leave it R12. Better performance and less wear and tear on the new compressor.
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  #3  
Old 06-11-2007, 05:38 PM
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Have the system completely flushed out. Use PAG 46 oil and refill with R12. Some people may say not to use PAG oils but experience shows that using the low viscosity PAG oils reduces failures significantly. The system has to have all the original mineral based oils removed as you never want to mix PAG and mineral oils together. A good solvent flush is required to be sure that all the mineral oil has been removed.

The combination of PAG 46 and R12 will give you the best performance and life possible.

You will need a good flush anyway since your compressor no doubt has shed all sorts of debris through out the system. If you don't flush out the system before replacing the compressor and drier the new compressor won't last long.
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  #4  
Old 06-11-2007, 06:03 PM
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Quote:
Originally Posted by dpetryk View Post
Have the system completely flushed out. Use PAG 46 oil and refill with R12. Some people may say not to use PAG oils but experience shows that using the low viscosity PAG oils reduces failures significantly. The system has to have all the original mineral based oils removed as you never want to mix PAG and mineral oils together. A good solvent flush is required to be sure that all the mineral oil has been removed.
Interesting advice. For the last 15 years I've only read that PAG and R-12 are not compatible. Care to share the source of your information?

- JimY
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  #5  
Old 06-11-2007, 06:33 PM
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PAG was developed for 134a but it has several advantages over the old mineral based oils that have been used for decades with R12. I know a shop that uses it exclusively because it reduces customer returns to almost nothing. Prior to that he was using mineral oil and had the "usual" number of returns. This guy has been in the business over 30 years. I respect his opinion. I learned about using PAG instead of mineral in a A/C service workshop I took as part of a continuing education course in refrigeration systems. I met a lot of people in the business of automotive A/C repair at the school.

Quote:
For the last 15 years I've only read that PAG and R-12 are not compatible.
The incompatibility exists between the two lubricants not between the lubricant and the refrigerant. PAG is compatible with either refrigerant. The incompatibility arises when there is a residual amount of mineral oil still in the system and you add PAG. Now you are in for trouble. If you flush clean and use only PAG you are better off than using mineral. Don't put PAG into a system that has not been completely flushed clean of all traces of mineral oil.

Quote:
The incompatibility between the aforementioned mineral oil lubricants also causes problems when introducing R-134a refrigerant/lubricant formulation into air conditioners or refrigerators, particularly automotive air conditioners, which already contain R-12 refrigerant/mineral oil formulations. This is because residual amounts of mineral oil and refrigerant typically remain in the system when changing an existing system from R-12 to R-134a. Thus, the incompatibility between the residual R-12 mineral oil formulation and the newly-introduced R-134 a/lubricant will be troublesome. Consequently, it would be highly desirable to be able to eliminate such incompatibility when retrofitting an existing R-12 system with R-134a.
My cars use the Denso 10p series and the recommended viscosity is 46. I have done 3 of my 5 cars and the oldest one is running for 6 years now. I live in Houston - it gets a lot of use. No problems or noise. I don't know what compressor you have but here is a table of recommended viscosity for various compressors.

The following is a list of recommended lubricants for compressor applications:

Behr/Bosch rotary compressors - Ester 100
Behr/Bosch piston compressors - PAG 46
Calsonic V5 - PAG 150
Calsonic V6 - PAG 46
Chrysler RV2 - Ester 100
Chrysler C171, A590 & 6C17 - PAG 46
Diesel/Kiki (Zexel) DKS, DKV & DCW - PAG 46
Ford FS6, FX15, FS10, 10P & 10PA - PAG 46
GM A6, R4, DA6, HR6, HT, V5 & V7 - PAG 150
GM V5 retrofit - PAG/FLR-118
Hitachi (all) - PAG 46
Keihin (all) - PAG 46
Matsu****a (all) - Ester 100
Mitsubishi FX80 - PAG 100
Mitsubishi FX105 - PAG 46
Nihon (all) - Ester 100
Nippondenso 6P, 10P, 10PA, 10P08E - PAG 46
Nippondenso SP127, SP134 & 6E171 - PAG 46
Nippondenso TV series - PAG 125
Panasonic (all) - PAG 46
Sanden SD500 & SD700 - PAG 100
Sanden SD710, SDB, TV & TRS - PAG 46
Seik-Seiki (all) - Ester 100
York/Tecumseh - PAG 46

Quote:
The Idemitsu Lubricants America Corporation Daphne Hermetic Polyalkylene Glycol (PAG) Series are synthetic lubricants uniquely formulated to provide unsurpassed lubricity, wear protection, and proper miscibility with ozone-friendly refrigerants. This formulation has been engineered to provide additional protection for wobble, rotary vane, swash plate, and scroll type automotive compressor and air conditioning systems where CFC (R-12) and HFC (R134a) refrigerants are used.
Compatibility statements;

http://www.pag-idemitsu-usa.com/page_200.htm
http://www.pag-idemitsu-usa.com/page_209.htm

A few other sites where information is more difficult to find;

http://www.patentstorm.us/patents/5372737-description.html


Try it - you will like it.
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78 Corvette Stingray - 3k
82 242 Turbo Volvo - Manual - 270k
86 300e 5 speed manual - 210k
87 420sel - 240k
89 560sl - 78k
91 420sel - 205k
91 560sel - 85k
94 GMC Suburban - 90k
97 Harley Davidson Heritage Softail - 25k
00 GMC Silverado 1 ton 30k

Last edited by dpetryk; 06-11-2007 at 07:31 PM.
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  #6  
Old 06-11-2007, 10:28 PM
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before anything you better see if you have black death.
is so then flushing will not help you.

george
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  #7  
Old 06-11-2007, 11:04 PM
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Quote:
Originally Posted by mbshop View Post
before anything you better see if you have black death.
is so then flushing will not help you.

george

Thanks,

Yes, I'll have to check that...I've been thinking about that potential problem since yesterday when it seized.
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  #8  
Old 06-12-2007, 01:12 PM
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Quote:
Originally Posted by dpetryk View Post
The system has to have all the original mineral based oils removed as you never want to mix PAG and mineral oils together. A good solvent flush is required to be sure that all the mineral oil has been removed.
Is it really possible to remove ALL the mineral oil? Seems like some would surely stay in some nook or cranny somewhere.
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  #9  
Old 06-12-2007, 04:29 PM
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Quote:
Originally Posted by brewtoo View Post
Is it really possible to remove ALL the mineral oil? Seems like some would surely stay in some nook or cranny somewhere.
There in lies the trick...it's nearly impossible to get All the old oil out.. To do the best possible job one must remove the expansion valve to get a proper flush.

Jonathan
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  #10  
Old 06-12-2007, 07:29 PM
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I have a 16v. I know the compressor on mine is different (higher reving engine) but I am guessing the rest is similar if not identical.

My manifold was leaking and had to be replaced. Went looking all around town for someone to do the work. Ended up taking it to MB. They convinced me to go with 134 on the new system. I was told up and down that R134 would give me the same if not BETTER cooling than R12. The shop manager even told me this (I have dealt with him quite a bit over the last several years). So I took the plunge.

After I gave them $2,100, they gave me my car and I'll be damned if that thing does not freeze my ass off. The highest I have had the fan on thus far this summer is the second speed. It has already hit mid 90's here in DFW and I am very satisfied.

The shop manager and the head tech there both told me that the biggest problem with conversions is people put the same amount of R134 in as the manuals say for R12 and the system is not designed for that. R134 expands more and there fore needs more room in the system. I think he said you are supposed to use 20% less or so. Any way, he also told me that R134 works at a lower pressure so there is less stress on the system (I figured on a 20 yr old car that cannot be a bad thing).

Bottom line is I have had the car back for a month now and I am very happy with the results. Seems to me that there is a good possibility that the folks who are having problems with 134 did not have the work done by someone who knew what they were doing. JMHO.

Good luck.
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  #11  
Old 06-12-2007, 10:09 PM
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Make sure there is no leak in the system before you take the compressor apart. Compressor could have failed because the oil may have leaked out over a period of time. If there is a leak, hopefully it is not behind the dashboard (I had it there and it took me months to finish the job).

I have changed from R12 to R134A on a 1987 260E a few years back. The steps are:
1. after removing the compressor and drier, flush the system a few times using compressed air and genuine flushing fluid, dont sweat to get all the oil out (thats what a mechanic at the dealer told me).
2. replace drier and compressor, make sure you use MB O-rings. MB O-rings are designed to withstand higher pressures of R134A. Use a rebuilt compressor, Hancock compressors are great. I have used them in two other cars (ML320 and Honda CRV). Use a MB drier.
3. use Ester oil in the compressor so that the remaining old oil will not cause a problem.
4. replace the schrader valves for low and high pressure sides, use MB valves
4. Vaccum and recharge with R134A
Caution: Do not use the gauges that you might have used for R12, use a new set of gauges. Also there is no need to change the valve adapters, leave them as the schrader valves.

R134A may take slightly longer to reach the cooler temperatures, but the convenience and cost of R134A far outweighs the benefits.

Good-luck
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  #12  
Old 06-12-2007, 11:26 PM
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use duracool!!

www.duracool.com
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  #13  
Old 06-12-2007, 11:31 PM
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R134a costs about half of the price of R12. Both of our cars are 134a from the factory, so I use it. But the price and availability are not good reasons to convert from R12.
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  #14  
Old 06-13-2007, 12:33 AM
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Quote:
Originally Posted by davidmash View Post
Any way, he also told me that R134 works at a lower pressure so there is less stress on the system (I figured on a 20 yr old car that cannot be a bad thing).
Lower pressure? Are you sure about that?
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  #15  
Old 06-13-2007, 01:28 AM
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R134a runs at higher pressures than R12.

Polyalkyl glycol lubricants can have a problem with chloride compounds such as CFC's and HCFC's. Any residual chloride left in a system has the potential of reacting with the PAG. R12, R22 are examples of these. There are DOUBLE END CAPPED PAG lubricants (Daphne is one brand, Japanese, I think) that many say will work with R12, but I would not use the plain old PAG. Double end capped referrs to the fact that the reactive ends of the Pglycol molecule are chemically "capped" to prevent halide (perhaps many anion) reactions.

Some would respectfully disagree with using ANY PAG with R12. I'm one.

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Last edited by jbaj007; 06-13-2007 at 02:36 AM.
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