A/C question on 126 chassis - PeachParts Mercedes-Benz Forum

GregZ · #1 02-14-2006, 07:52 PM

Hi All,

Again, he posting is about my 1983 380SEC.
I am wondering whether the A/C compressor can handle R134a? Is this just a swap fittings, make sure system is tight, replace drier, evacuate, fill with R134a conversion (obviously not in this order), or does the compressor/other parts have to be replaced as well? (I know on some BMWs, the compressor's seals cannot take the new oil associated with R134a - thus the quesion).
Please help...

420 SE · #2 02-15-2006, 04:49 AM

My understanding is that the seals would need replacing also - +/- other bits.

It's not as simple as replacing the fluid but I'm not sure exactly what is entailed.

mbdoc · #3 02-15-2006, 08:39 AM

MOST of the early R134a warnings WERE incorrect!

Conversion on any 1981 & later car with THAT A/C compressor is as simple as draining the old oil...flushing...adding new PAG 100 weight that is compatable with both R12 & R134a..pulling a vacuum & recharging with 70-75% of the original R12 spec.

Remember that that system should have a new drier with a PRESSURE switch as part of that conversion..

GregZ · #4 02-15-2006, 11:27 AM

will all drier's accept a pressure switch or is this a special drier with a pressure switch?
E.g., would something like this be okay:

http://cgi.ebay.com/ebaymotors/Mercedes-A-C-drier-W126-560SEL-420SEL-300SD-500SE-dryer_W0QQcmdZViewItemQQcategoryZ46094QQitemZ8038367908QQrdZ1

Thanks,

Greg

Al Magaloff · #5 02-15-2006, 12:44 PM

Greg, I would ask to see pictures of the other side. Not all R/D's will accept a switch. I would buy one from Fastlane, and pass on the $13 Ebay special!

Pete Burton · #6 02-15-2006, 12:57 PM

Greg, although the compressor can "handle" 134a, it won't last as long and your hoses won't either. Especially as you are in Ft. Worth, a much better option will be to get a 609 cert online (costs about $15) and then get R12 and keep it that way. In the end, it will be cheaper for you and it will work better.

GregZ · #7 02-15-2006, 01:06 PM

neat - where can I get certified for that - any hints?

Thanks to everyone

TX76513 · #8 02-15-2006, 01:25 PM

www.epatest.com/e_home.html

If you do decide to flip to 134 swap both drier and compressor. They make 134 compressors for a reason.

Hatterasguy · #9 02-15-2006, 03:31 PM

My SDL was converted over to R134 in 1994 by a dealer. By the looks of it at the time they swapped out most of the lines and the compressor. Considering a new compressor for this thing is like $700 I have no problem with that.

It seems to work well enough, but that AC on these cars is pretty weak. American cars will freeze you out, for some reason these won't.

Al Magaloff · #10 02-15-2006, 06:40 PM

A 134 car will never be as cold as R12. DieselGiant has some stuff (R12 substitute) he claims works pretty well, but I've never used it. I'm R12 legal, and can buy and dispense all I need too. I would keep my R12 car R12 as long as I could.

GregZ · #11 02-15-2006, 09:44 PM

Thanks for the cert info. I am all certified now. The tools I have anyway.

Al Magaloff · #12 02-16-2006, 05:08 AM

You can find R12 for a decent price from one of the Ebay bozos.

Kebowers · #13 02-19-2006, 12:41 AM

For a system designed for R-12--keep it R-12 if at all possible. You may not be happy with the cooling performance and longevity with R-134a installed. It is VERY difficult to get all the R-12 oil (a special mineral oil) out of the system, and just a little is all that is needed to gum up a system filled with R-134a and its synthetic oil. And your R-12 hoses will leterally 'seep' R134a through their pores, causing annual re-charges (complete with legally mandated leak testing, in all probability.

A properly designed system running 134a is just as cold as one running R12. It just takes larger expansion valve, evaporator and condensor and compressor.

Al Magaloff · #14 02-19-2006, 05:54 AM

"A properly designed system running 134a is just as cold as one running R12" That is true, but not going to happen on a converted car. So I stand by my statement, but will modify it some, so it doesn't get tweaked around again. "A car that was originally designed for R12,converted to 134, will never be as cold as it was on R12".