[R129 SL] '91 500SL A/C problems

[Porterb7 at aol.com]

I will comment generally on the changeover.  I know that  the new freon 
R134A is under much lower pressure than the old R12 and has been  used in cars 
since 1996.  It is my understanding that every connection has  to be updated 
and the system pressure tested and then purged of the R12.   The two 
refrigerants don't work together.  The system may have to cleansed  as well.
    I don't know much about this site, but  I have had good luck in getting 
responses on _http://mercedesforum.com/forum/_ 
(http://mercedesforum.com/forum/) . I  have a 96 SL 500
 
 
In a message dated 7/9/2011 7:18:48 P.M. Eastern Daylight Time,  
Oldbenz1 at aol.com writes:

Recently the A/C in my '91 500SL began to blow warm air.  A local  M-B 
repair facility quoted me more than $2500 for the fix.  The major  problem is a 
leaking hose at the compressor but of course, they apparently  subscribe to 
the philosophy "never let a cash cow escape unmilked" so their  estimate 
included replacing a laundry list of hoses, seals, fittings, dryer,  etc., etc. 
ad infinitum.   Part of the "fix' included a conversion  from freon12 to 
R134.  I've seen kits offered to accomplish this  conversion for less than 
$50.00 and I would guess that the estimate  I  received for that part of the 
job was grossly inflated.  I suspect that  to replace the hose in question is 
one of those things that requires many  hours of labor, and I'd bet that 
suppliers of after-market parts sell the same  hose for a fraction of the M-B 
price.   Here's are my  questions:  if anyone out there has been involved in 
a similar problem,  can you give me tips about the difficulty of replacing 
the hose, and do you  have a source for the parts at humane prices?   I have 
a fair amount  of experience and may consider doing the job myself, although 
I do not have  the equipment to charge and test the system once the new 
parts are  installed so would have to have that done by a professional A/C  
shop.    Any suggestions would be appreciated.  
Rich Splaine 


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