[W126 Coupe] 1985 euro version 500 SEC A.C conversion to R134 from R 12

[Doug Gavin]

jeffrey maniff wrote:

> Jim,
> Thanks, I appreciate the words of wisdom and I am going to hunt down a 
> supplier of R12 and just recharge the existing system but I will 
> replace the receiver drier as it should be since I replaced the broken 
> compressor.
> Thanks again,
> Jeff
>
>
>
>> From: jralex at ix.netcom.com
>> Reply-To: jralex at ix.netcom.com,Mercedes Coupes Mailing Lists 
>> <mbcoupes at mbcoupes.com>
>> To: Mercedes Coupes Mailing Lists <mbcoupes at mbcoupes.com>
>> Subject: Re: [W126 Coupe] 1985 euro version 500 SEC
>> Date: Sun, 3 Sep 2006 02:17:23 -0400 (EDT)
>>
>> Jeff, I agree with Jonothan. Just recharge with R-12. It cost much 
>> more per pound but worth it, all things considered. You already have 
>> some mineral oil(petroleum based) throughout your system and that IS 
>> to be considered. Most problems with conversions for all cars over 
>> the years has been related to a complete lack of knowledge of 
>> lubricant compatibility. PAG polyalkene glycol is not compatible with 
>> anything at all. Even additives such as antiwear,EP, antifoam etc. 
>> cannot be mixed with it. However it is miscible with gases and has a 
>> film strength greater than any other so with a completely clean 
>> system it will work. Polyolester is also not compatible with 
>> petroleum but is used with R134. The high pressure-lowpressure 
>> fittings are differant for R134 so they would need to be changed. Our 
>> old style hoses will slowly leak the smaller molecule R134.. Best 
>> thing to do is replace the dryer, put a vaccum on the system and let 
>> R12 back into it at the appropriate weight. Too much or too little is 
>> a problem. Just right is the only way to do it. Find a local 
>> independent MB tech who does R12. Jim Alexander
>>
>> -----Original Message-----
>> >From: jeffrey maniff <jsman24 at hotmail.com>
>> >Sent: Sep 2, 2006 12:58 PM
>> >To: mbcoupes at mbcoupes.com
>> >Subject: [W126 Coupe] 1985 euro version 500 SEC
>> >
>> >Help,
>> >Does anyone know what the protocol is to convert over a gray market 
>> 500 sec
>> >AC to today's R134.  I replaced the compressor which fits and is 
>> working but
>> >I have not changed the dryer/receiver or did anything with the pipes 
>> but the
>> >R134 freon will not no into the system.  DId I forget something?  
>> Also, If I
>> >need to change the dryer/Receiver, does anyone know where to get one 
>> in a
>> >hurry? or even not in a hurry just to get one.  Please help
>> >Thanks,
>> >Jeff Maniff
>> >
>> >_________________________________________________________________
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>> >
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I find it very interesting that not just two weeks ago this very topic 
came up and I passed along the advice from  my A.C. guy, (which is all 
he does).  He gave me stern warning not to convert my 90 560 SEC  from 
R-12 to anything else with the caveat that,  to a person that he had 
done this for in '80s to early '90s M.B.s (with his warning not to) they 
had come back with the complaint that it just was not cooling as it used 
to.  I'm in Houston so the humidity is very high as is the ambient temp 
is above 95 degrees every day in July and August. The very high humidity 
may be a major factor in results.  I'm glad to see that Jim and Jonathan 
are advising the same in spite of the numerous folks that had responded 
to my e mail with adamant disagreement supported with  successful 
experience with other products such as Duracool that had worked for 
them.  It may be the environment that has the biggest impact on the 
results and that has to be taken into consideration with this decision. 
In Houston, I'll stick with my R-12 as long as I can get it. I bought 5 
cans today at a swap meet for $100. My A.C., guy charges $40 per lb. or 
can,  so I consider myself lucky to have found this R-12. When my stash 
or the general supply runs out, I too, will have to make another 
decision. Until then , riding cool in Houston.  It was cool today at 92 
degrees, fall is in the air. Just my my 2 cents.

Doug