I need to replace the condenser in my 300SD, so I'm thinking of going with the newer one for better cooling. I then saw someone say that you can use R134a with the newer condenser. Is this correct? What would be the consequences of doing so? Would I break anything? I don't think that I'd ever be dialing the car below 75° F, and we only have nasty heat here in New England for a few months, though I would want the car to keep at the above mentioned temperature during those months. I know that I can get a license to buy R12 for $25 after taking a test, but I don't know how soon I'll have time to study that. I also have a can of R134a that our newer cars don't need, and it would be nice to just use it on this. I believe that that can already has oil in it as well.

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"Senior Luna, your sense of humor is still loco... but we love it, anyway." -rickymay ____ "Your sense of humor is still loco... " -MBeige ____ "Señor Luna, your sense of humor is quite järjetön" -Delibes

1982 300SD -- 211k, Texas car, tranny issues ____ 1979 240D 4-speed 234k -- turbo and tuned IP, third world taxi hot rod

2 Samuel 12:13: "David said to Nathan, “I have sinned against the Lord.” And Nathan said to David, “The Lord also has put away your sin; you shall not die."

Stay with R12, if possible. My W126 has 134A and I would switch back if I have to break the system.

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Present
1987 300SDL
1991 300SL
1990 560SEL
2001 ML320

Past
1969 200D 1979-82
1983 300SD 1984-85
1972 250C 1982-02
1995 S350 2011
1997 S320 2012

Why?

__________________
"Senior Luna, your sense of humor is still loco... but we love it, anyway." -rickymay ____ "Your sense of humor is still loco... " -MBeige ____ "Señor Luna, your sense of humor is quite järjetön" -Delibes

1982 300SD -- 211k, Texas car, tranny issues ____ 1979 240D 4-speed 234k -- turbo and tuned IP, third world taxi hot rod

2 Samuel 12:13: "David said to Nathan, “I have sinned against the Lord.” And Nathan said to David, “The Lord also has put away your sin; you shall not die."

System was designed for R12. Cools better.

If you put in a modern condenser, then R134a should work fine. Using R134a in an old style condenser designed for R12 won't give very cold air. I think you will be okay if you install the modern condenser, new hoses, and use a compressor that will handle R134a. This is what I plan to do.

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1967 W110 Universal Wagon, Euro, Turbo Diesel, Tail Fins, 4 Speed Manual Column Shift, A/C
1980 W116 300SD Turbo Diesel, DB479 Walnut Brown, Sunroof, Highly Optioned, 350,000+ Miles

you will still need new hoses, and the oil in the system needs to be changed as well

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1982 300D Turbodiesel, daily driver. Mods so far: Fram 8038 paper filter, 4 brake light mod, Gen II w126 (front) rotors/calipers, boost turned up to 12lbs, non-egr manifolds, water/methanol injection, 4-speed manual
1980 300SD Turbodiesel, project car, nearly ready to hit the street

1974 240D, New paint

There in a user of this forum who made two condensers work so all refrigerant is properly cooled down and his A/C worked super cold after that with 134.

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2012 BMW X5 (Beef + Granite suspension model)

1995 E300D - The original humming machine (consumed by Flood 2017)
2000 E320 - The evolution (consumed by flood 2017)

yup, it's not just that the stock condenser is not modern, it's that it does not have the surface area to reject the heat 134 makes when cooling. adding in additional condenser surface area weather it's from a modern condenser, or an additional one, does the trick.

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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 190D 2.5Turbo
1987 190D 2.5-5SPEED!!!

1987 300TD
1987 300TD
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!

consider propane / isobutane mix, it is cheaper and characteristics are closer to R12 aside from inflammability. Sometimes you can buy it in cans marketed as drop-in R12 replacements (usually it is hard to see fine print saying that the $20 can contains $0.15 of propane and nothing else)

I HAVE A 50 # CYCLINDER OF R-12 FREON I WILL SELL FOR $600. THAT IS $12/ POUND. I BOUGHT IT WHEN I HAD 1979 SL. HAVE SOLD THE SL NOW WILL SELL FREON. LOCAL PICK UP ONLY. PANAMA CITY BEACH FL. 32413 850-233-7443. HAROLD

Jooseppi: You haven't mentioned the parts of this story in which you flush the entire system completely, replace all seals, and only then recharge with 134a... (!!)

By 'can' of R134a, I hope you mean one containing the couple of pounds of 134a you'd need for a complete recharge. It's best to recharge these systems by weight of refrigerant, from my understanding.

FWIW, my 83 300SD was converted to R134a about 15 years ago, and worked fine. Probably never as cold as theoretically possible with R12, but quite good. It developed a slow leak last year, and the compressor clutch died a month ago. Have now embarked on the complete Flush, Re-seal, Compressor Replacement, Recharge process!

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'83 300 SD
'68 Triumph TR 250 - The only car I ever loved more than the Mercedes; who needs electricity, anyway? - Damn, why did I sell it?!
'59 Jaguar 3.4 'Le Chat Noir' - Damn, why did I sell it?!

It's difficult to make predictions, especially about the future.
- Niels Bohr

Why re-invent the wheel? R12 is a better refrigerant all the way around, and is readily available. It requires less power to run the compressor, and its oil is not as hydroscopic, making it less corrosive on components. If R12 was NLA, that would be another story. Why do all that extra work for no benefit?

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'83 300D, 126K miles.

Last time I bought

R12 it was for $20/ (12/18-cant recall)oz can
R134A is about on par with that
ES-12A is about $7/can

Here is my experience

In the stock system:

R12 is the best no doubt.
R134A is merely OK, it sucks at idle because of low air movement. Its OK at speed.
ES-12A also sucks at idle, but does pretty well at speed.

I have ES-12A in my 190E. The vent temps can go into the mid 30's on an ~80F day. I'd say it does pretty well. When I first bought the car I had R12 charged into it. It leaked out in a year. I had Freeze12 put in, it too leaked out in a year (its a R134a blend after all) I put ES-12A in and it didnt leak out at all. Yes there is probably a leak but at the time I was not spending the time/money to deal with it.

I have Es-12A in the one 300SD. All stock system with R4 compressor. At idle speed it is useless. At 40mph+ its comfortable. I suspect you'd be OK in the New England area with it and for <$10 a can..why not ?

IMO, the PROPER way to go is to convert to a nicer Sanden compressor and use a larger condenser and larger fan assembly AND to clean out the evaporator but that is oodles of work and money.

The 420SEL has a R12 system. Its probably the coldest vehicle aside, but I suspect it has a leak as well somewhere.

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82 300SD 145k
89 420SEL 210k
89 560SEL 118k
90 300SE 262k RIP 5/25/2010
90 560SEL 154k
91 300D 2.5 Turbo. 241k
93 190E 3.0 235k
93 300E 195k

It depends on whats wrong with his current system.. If its low, and he fills it back up without fixing any leaks its a waste of comparatively (to ES-12A or other alts) expensive R12.

If he is going to change to the larger condenser, change all the seals and do the job properly than I would support the usage of R12.

If he's going to just dump R134A in without doing anything..it will leak out regardless unless the hoses and seals are changed to the proper type which is kind of expensive and time consuming I think.

If he just wants AC to work now without all that effort I would just throw ES-12A at it for the short term.

EDIT: One of the most important things is to make sure the condenser AND the evaporator are clean. When I cleaned my 190E's evaporator cooling and airflow improved tremendously. The air flow feels so much different than before ..less disturbed more "full" if you will.. I wish cleaning my 126' evaps were as easy

__________________
Cruise Control not working? Send me PM or email (jamesdean59@gmail.com). I might be able to help out.
Check here for compatibility, diagnostics, and availability!

(4/11/2020: Hi Everyone! I am still taking orders and replying to emails/PMs/etc, I appreciate your patience in these crazy times. Stay safe and healthy!)


82 300SD 145k
89 420SEL 210k
89 560SEL 118k
90 300SE 262k RIP 5/25/2010
90 560SEL 154k
91 300D 2.5 Turbo. 241k
93 190E 3.0 235k
93 300E 195k

My two cents, if I had no source for R12 and I had to choose between r134a and Enviro-Safe (ES-12A). I choose Enviro-Safe. Especially if you are still running the R4, lower pressure would help the motor out immensely along with better cooling capability.


.

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1983 123.133 California
- GreaseCar Veg System