[W126 Coupe] 1985 euro version 500 SEC

[jralex at ix.netcom.com]

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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