A/C Leak at Back of Compressor - PeachParts Mercedes-Benz Forum

npretnar · #1 04-11-2013, 12:32 PM

Okay, so I'm considering tackling the A/C system. Found two leaks identified by dye: one at the schrader valve -- easy replacement and another at the back of the compressor which seems to be coming from where the hoses connect to the compressor. Here's what I know about my A/C system:

It worked last year but not anymore.
Converted to R-134A within the last seven years.
Drier is fairly new and I never noticed any bubbles in the system at all last year.
Compressor is R-4 and looks original.
Hoses too, look original.

What I am considering doing is pulling the hoses and having them rebuilt by a local hydraulics shop because I think the high side hose is leaking at the crimp between the rubber and metal connection behind the compressor. Then I want to replace seals and recharge.

My question is, can I replace the seals I see as leaking and get away with it? And, what color seals do I need to use considering I will be recharging with R134A?

Thanks for the help, guys!

mach4 · #2 04-11-2013, 12:45 PM

Why not use this opportunity to do an upgrade to a current technology compressor? What used to be a nightmare of fabrication and design is now a bolt in proposition. It will cool better, take less power, last longer, be specifically designed for 134 (if you want to stay with that), and use standard fittings.

Just a thought...

Search Sanden and you'll find a wealth of information.

npretnar · #3 04-11-2013, 02:19 PM

Will look into it.

97 SL320 · #4 04-11-2013, 04:54 PM

The Schrader valve needs to have a sealing cap installed to prevent leaks and to keep dirt out.

Changing the seals where the hoses attach to the compressor is easy. Bleed the system, remove the center bolt then change 2 o rings.

134 systems use green o rings.

I tend to change any o rings that I can get to. Some R-4 compressors have a high side pressure switch on the back, this o ring can be a leaker due to the high heat it sees.

BillGrissom · #5 04-12-2013, 12:21 PM

Quote:

Originally Posted by mach4

Why not use this opportunity to do an upgrade ... now a bolt in proposition.
Search Sanden and you'll find a wealth of information.

The Klima kit comes w/ all hoses, but is fairly pricey (search ebay). I bought Rollguy's Sanden bracket, but haven't installed yet (son has car). It requires fabbing custom hoses. I have a concept I'll post if it works.

Let us know if it turns out easy for a hydraulic shop to rebuild your existing AC hoses. I have read that the M-B hoses and fittings are a metric size that isn't readily available in the U.S. Some have had to weld the M-B tube ends to standard U.S. tubing. It might be easier to have hoses made that run all the way to the next hard fitting. Look at what the Klima kit does. The connection at the R4 compressor is a standard "GM Pad", so you can buy fittings for that, but connecting to the rest of the car is harder.

vstech · #6 04-12-2013, 12:30 PM

you may not have noticed any bubbles, but the 123 with a 134 "conversion" will always have bubbles... ignore them.

what seals your compressor would need depend on what compressor is in there...

if you have the original 1983 hoses, 134 will always leak out. new hoses with a barrier to 134 are needed to slow leakage.
also, the 123 condenser is inadequate to remove the heat with 134 installed... I recommend just cleaning, and flushing the lines and coils, installing mineral oil, and putting the R12 that originally came in the car back in...
unless you live up north, then you don't care much how well the A/C works...

npretnar · #7 04-12-2013, 08:40 PM

The idea of r12 scares me considering I don't wanna drop a bunch of $$$ into it only to have it leak out in a year, especially considering I have old, original components. I don't know, I'm thinking about just taking the belt off and scrapping the AC system altogether. I don't really like AC that much anyway and we rarely use it at home unless it's really ******* hot.

For an R12 reversal, wouldn't I need to replace more than just seals?

vstech · #8 04-12-2013, 10:19 PM

unlikely.
the typical R134 "conversion" is:
1. remove the R12
2. install 134 style fittings, and the warning sticker it's been converted.
3. evacuate system, add some 134 compatible oil and charge with 80% of original charge...
4. deal with the inadequate cooling of the "converted" system.

vstech · #9 04-12-2013, 10:20 PM

all the systems I've converted back to R12 hold their charge.
I pressure test the system with dry nitrogen for 24 hours before charging with 12 to verify it's leak free.

ROLLGUY · #10 04-12-2013, 11:05 PM

Quote:

Originally Posted by mach4

Why not use this opportunity to do an upgrade to a current technology compressor? What used to be a nightmare of fabrication and design is now a bolt in proposition. It will cool better, take less power, last longer, be specifically designed for 134 (if you want to stay with that), and use standard fittings.

Just a thought...

Search Sanden and you'll find a wealth of information.

Agreed 100%

BillGrissom · #11 04-12-2013, 11:42 PM

As an alternative to R-12, read up on HC mixtures (mostly butane). I have used Duracool for years in several cars, including a W123 w/ R4 compressor. Freeze-12 (sp?) is another. It works slightly better than R-12, and is compatible with either mineral or PAG oil, plus any residual R-134A. You can read all kinds of imagined horror stories, mainly from people who have never tried it. Most humorous reading is on the EPA website, where they don't say it is unsafe, just "not evaluated". You must convert yourself since shops must follow byzantine EPA rules, plus most oppose it for various reasons (too easy?). Works with your R-134A fittings. If still scared, you can often find R-12 reasonably priced. It isn't the gold that many sellers imagine. I even found a can on a bench while out jogging a few years ago.

ROLLGUY · #12 04-13-2013, 12:49 AM

Quote:

Originally Posted by BillGrissom

As an alternative to R-12, read up on HC mixtures (mostly butane). I have used Duracool for years in several cars, including a W123 w/ R4 compressor. Freeze-12 (sp?) is another. It works slightly better than R-12, and is compatible with either mineral or PAG oil, plus any residual R-134A. You can read all kinds of imagined horror stories, mainly from people who have never tried it. Most humorous reading is on the EPA website, where they don't say it is unsafe, just "not evaluated". You must convert yourself since shops must follow byzantine EPA rules, plus most oppose it for various reasons (too easy?). Works with your R-134A fittings. If still scared, you can often find R-12 reasonably priced. It isn't the gold that many sellers imagine. I even found a can on a bench while out jogging a few years ago.

The biggest problem with those "designer" refrigerants that I can see is that NO reputable shop will recycle them. Every shop that has a recycling machine will test the contents of the system before recycling, and will not risk contaminating their R12 or R134A refrigerant containers with anything else. If the refrigerant is not recyclable, then there is no recovering any of the refrigerant before any repairs are made. That being the case, many shops will say to bring the car back with the system empty, and not ask any questions as to how it got emptied of the designer refrigerant (we all know how this happens most of the time). Just something to think about. As far as cooling with 134A in a 123, I have had pretty good success with the systems I have converted. My 126 seems to cool very well, and a couple 123's are still cooling satisfactorily with 134A and the stock condenser.

Hit Man X · #13 04-13-2013, 08:58 AM

I have nothing good to say about the R4.

The Sanden conversion is the best thing I have done for my 300SD, bar none. Now it is an all weather car.

I went with a kit from Klima and it is working great. I was the first to utilize their kit on the W126 best to my knowledge, so I had to do a bit of 'beta testing' if you will, but was worth it in the end. It was not a bracketry issue, just fiddling with that high side hose that passes through the core support. I think it had something to do with my ECE headlamps too, I forget.

Remember now, the fittings are all standard size. I highly recommend buying that Master Cool manual crimper for ~$150 to build your own hoses. It will pay for itself. Mine was purchased from Amazon. I have built three systems with it so far.

All of my pictures should still be online here and I still use R12. If not, I would use 134A with a parallel flow.

97 SL320 · #14 04-13-2013, 02:08 PM

To quote an old salvage yard guy about the R4. " They was no good when times was good. "

Same guy different item when asked for a 3 speed manual transmission. " 55 Pontiac 3 speed? why do want that? they was no good in 55. . . "

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