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  #1  
Old 08-13-2001, 10:49 AM
Robert Boyer
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A/C refrigerant

Have an '88 420 SEL, which I purchased about 14 months ago.

Over the weekend, I put 2 cans of R-134A into it. Simple. No hassles. Car seems to cool better and faster, especially noticeable after sitting in the sun at midda. (which it would take much longer, before).

My question: This car may very well have an old freon-based (R-12) system. I don't know. Although what I did may not help-out all that much as per the cooling, was putting R-134A particularly harmful? I don't think so. Just would like some feedback. Thanks.
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  #2  
Old 08-13-2001, 11:18 AM
LarryBible
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Did this car have r134a service connections already installed? Did you use an r134 manifold and guages?

If this system was still R12, how did you get the r134 into the system?

If this was originally an R12 system, and this was the first introduction of r134 into the system, there are other things that you should do.

At a minimum, you should remove as much oil from the compressor as possible and replace with ester oil, then evacuate, use r134 connection adapters and charge. The mineral oil originally used with R12 is not compatible with r134 and will knock out the compressor.

Give us more information so we can help you further.

Good luck,
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  #3  
Old 08-13-2001, 11:42 AM
Robert Boyer
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Larry:

All the connectors and connections fit. In fact, the intake plug looked rather new. So I suspect that the system was R-134A converted already.

However, for assurance, you mentioned evacuating the compressor oil and refilling it with proper new oil. Can you please, if possible, run me through exactly what I need to do on this? Is it a simple DYI?

Thanks.
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  #4  
Old 08-13-2001, 10:47 PM
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Join Date: Dec 2000
Location: Mountain Island Lake, Charlotte NC
Posts: 376
Larry,
While you are explaining..does the 86 560sl model use r12?
rob
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Rob Armstrong, Charlotte, NC
Mountain Island Lake
RobAinCLTNC@hotmail.com

2004 VW Passat GLS TDI-50k
2006 Honda Odyssey EX-L 7k
FOR SALE 1991 300TE 228k

2003 Subaru Outback 57k Silver/Black-SOLD
2005 C230K 18k Pewter/Grey-SOLD
1997 E420 108k Black/Grey-SOLD
1986 560sl 200k Black/Palimino-SOLD
1985 300sd 340k-SOLD
1979 240d 170k-SOLD
2000 Volvo V70XC-POS couldn't sell fast enough
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  #5  
Old 08-14-2001, 01:26 AM
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Join Date: Mar 2000
Posts: 529
'86 560 SL was factory equipped with R-12.
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  #6  
Old 08-14-2001, 09:03 AM
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Join Date: Dec 2000
Location: Mountain Island Lake, Charlotte NC
Posts: 376
how difficult is it to switch this over to r134?
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Rob Armstrong, Charlotte, NC
Mountain Island Lake
RobAinCLTNC@hotmail.com

2004 VW Passat GLS TDI-50k
2006 Honda Odyssey EX-L 7k
FOR SALE 1991 300TE 228k

2003 Subaru Outback 57k Silver/Black-SOLD
2005 C230K 18k Pewter/Grey-SOLD
1997 E420 108k Black/Grey-SOLD
1986 560sl 200k Black/Palimino-SOLD
1985 300sd 340k-SOLD
1979 240d 170k-SOLD
2000 Volvo V70XC-POS couldn't sell fast enough
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  #7  
Old 08-14-2001, 09:30 AM
LarryBible
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If the system was already converted, is there an r134a retrofit sticker somewhere under the hood or on maybe a door jamb. The sticker is supposed to be added upon conversion. If you can find it, it will tell you what kind of oil and how much was used. It should have ester type oil in any 12 to 134 conversion.

If this was not done, or if you cannot verify that it was done, the system, at a minimum, should be bled, oil poured out of compressor if you can get any out, and add about six ounces of ester oil. The system should then be evacuated and recharged.

The mineral oil used with R12 will not work well with 134 and can knock out the compressor.

For the other car, the same minimum procedure should be followed to convert. To convert the fittings you can get a set of fittings almost anywhere, but don't use one of the "kits" with suicide hose, fittings and refrigerant. It sounds like you have a set of r134 manifold guages, if you don't that's what you need.

A complete changeover procedure would involve, bleeding, disconnecting everything and flushing, replacing filter-drier, replacing with ester oil, evacuation and recharge.

R134 is much more susceptible to the development of acid if moisture is not completely removed before charging. Pumping down the system with the car in the heat for 24 hours would not be overkill. If any moisture is left in the system, it can combine with the refrigerant to produce an acid which can corrode the system from the inside out.

Good luck,
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  #8  
Old 08-14-2001, 08:08 PM
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Join Date: Dec 2000
Location: Fairfax County, Virginia
Posts: 856
Hi Guys,

I have heard there is a new replacement for R-12 called R-406a.

It is reportedly a better replacement than 134a and requires fewer changes - nothing except replacing the fittings.

Anyone heard about this or done a conversion to 406a?

George
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  #9  
Old 08-15-2001, 10:33 AM
LarryBible
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The best, most active a/c discussion forum is at www.aircondition.com. They mention 406, but it doesn't seem to be very widely accepted. There is much more known about 134. If you're going to change, 134 is relatively cheap and there is a good knowledge base of information to draw from. If you try 406, you are out there flying around on your own. At least at this point you are.

Good luck,
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  #10  
Old 08-15-2001, 10:43 AM
Registered User
 
Join Date: Dec 2000
Location: Mountain Island Lake, Charlotte NC
Posts: 376
Hey Larry,
About how much does the conversion cost at a Mercedes Shop..not dealer...
Thanks
__________________
Rob Armstrong, Charlotte, NC
Mountain Island Lake
RobAinCLTNC@hotmail.com

2004 VW Passat GLS TDI-50k
2006 Honda Odyssey EX-L 7k
FOR SALE 1991 300TE 228k

2003 Subaru Outback 57k Silver/Black-SOLD
2005 C230K 18k Pewter/Grey-SOLD
1997 E420 108k Black/Grey-SOLD
1986 560sl 200k Black/Palimino-SOLD
1985 300sd 340k-SOLD
1979 240d 170k-SOLD
2000 Volvo V70XC-POS couldn't sell fast enough
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  #11  
Old 08-15-2001, 05:05 PM
LarryBible
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The price will be determined by many things. I would expect that some shops might just extract the R12, replace the oil, evacuate and recharge. This would be the absolute minimum procedure that you should expect.

Others will insist on a filter drier, flushing of the entire system, oil replacement and recharge.

I would expect the first to be about $150 if the system has no leaks or other ills that need to be dealt with. I wouldn't want to guess at the second one.

The problem is that, usually people do not change to r134 because they woke up one day and thought that it would be a neat thing to do. They are usually doing it because their a/c no longer makes the car cool. This means that there is a leak or other ill that must be repaired at the same time. This means that it is impossible to know what it will cost.

The a/c on my Vette stopped cooling a few weeks ago. I had already charged it with R12 and put in flourescent dye when I did. When it stopped cooling the second time I looked for the leak with the UV lamp and found a $10 pressure cycling switch leaking like crazy. I removed the R12, replaced the switch, put in Ester oil, evacuated and charged. It now works great. The switch, oil and r134 probably cost me about $28. I don't know what a shop would have charged. I expect that they would have had a few hours in it, so probably about $150 labor plus material. If I were them I would have replaced the filter/drier if it were on a customers car, so that would've probably added $50 or so.

In the case of the Vette, I was lucky, it could have just as easily been the compressor or evaporator leaking which would add no telling how much expense. So, you never know.

Hope this long winded explanation is helpful,
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