Someone put 134 in my A/C ('84 SD) can I "go back?"

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Someone put 134 in my A/C ('84 SD) can I "go back?"

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Mercedes >> Mercedes Benz Models >> Diesel Discussions >> Someone put 134 in my A/C ('84 SD) can I "go back?"

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Someone put 134 in my A/C ('84 SD) can I "go back?... - 6/16/2007 6:42:51 AM

ajrn

Posts: 29
Joined: 2/21/2007
Status: offline

I looked at the dieselgiant site's information on A/C repair, and dropped the cash for the DVD. (BTW-- it's probably worth the bucks, if you've never done "ANY" A/C repair!)

I was getting things together to get started, new drier, new expansion valve, refrigerant and 'oil..' I was going to draw it down today-- and get to work this afternoon.. My freeze-12 (drop in "Freon" replacement) arrived a couple days ago..

Here's my problem.. Uncapped the lines, to find one has been "retrofitted" to 134a.

My questions are:

1) can I just wrench that off?? It looks like it's just a screw on fitting.

2) the BG refrigerant oil is compatible with both 134 AND R-12 "freon" so I'm thinking that isn't an issue..

3) do I need to replace the receiver drier and expansion valve, and pretty much, go on with my life??

BTW-- my compressor clutch connected and ran for a few seconds without horrific noises.. I think I'm okay there...

I'd really PREFER to go back to the R12 (Freeze 12) setup. One, it's already paid for, two-- it's closer to what 'Ma Benz designed the system for.. 134 seems fine, for what it's designed for-- I've never been impressed with it for retrofits... I did a couple for others when Freon first became scarce, and before reasonable alternatives like Freeze-12 were available. Their systems didn't work 'as well' or blow 'as cold...' The compressors seemed to die about 2-3 years later.. We told ourselves they were old compressors-- but I now understand that 134 operates at higher pressures-- and that stresses the compressor more..

Anyway-- any help would be appreciated..

AJ

Post #: 1

RE: Someone put 134 in my A/C ('84 SD) can I "go b... - 6/17/2007 1:50:02 PM

Drrty240D

Posts: 160
Joined: 7/30/2006
Status: offline

You'll probably find opinions in every direction, but I was told the following by a very reputable mechanic (and friend) with 40+ years experience in general auto mechanics. Eventually the R134a refrigerant will damage a system designed for R12. From what I remember the R134a charge will liquefy the dessicant in the receiver-drier after exposure for several years. Then the liquified dessicant begins to move thru the system and damages the compressor. IMHO this is what eventually kills the compressors.

I'd say evacuate the system ASAP and try to get out as much oil as possible. This can be tough, but I think it's a worthwhile exercise. Then change your receiver-drier and expansion valve and remove the retrofitted 134a valve(s) and go back to the Schraders. Evacuate again, check for proper # Hg vacuum for your system. Recharge with known compatible lubricating oil and R12 (if you can find it - it IS out there) or R12 replacement refrigerant like Autofrost, Enviro-Safe or another CFC-12 substitute.

(in reply to ajrn)

Post #: 2

RE: Someone put 134 in my A/C ('84 SD) can I "go b... - 6/17/2007 3:02:41 PM

ajrn

Posts: 29
Joined: 2/21/2007
Status: offline

Pretty much what I thought, and my plan..

I'm going to use "Freeze 12" refrigerant and BG products compressor oil.. The 'retrofit' valve damaged the threads on my upper line, but the gauge manifold still sealed okay..

I have the feeling someone likely just SHOT the 134a in there-- ugh ugh ugh..

I already had a new receiver dryer and expansion valve.. I'm replacing both the switches on the dryer-- as I really want to be DONE, when I'm done dinkin' with this...

I may shoot 134 into my '240D though.. The rust will kill the car-- before 134 could kill the compressor!

AJ

(in reply to Drrty240D)

Post #: 3