lost refrigerant, what to swap? - PeachParts Mercedes-Benz Forum

JHZR2 · #1 02-14-2013, 05:06 PM

Hi,

My 82 300CD had perfect AC. Never needed to top up or do anything. Unfortunately the car has sat for ~1.5 years, so something must have dried out and allowed R12 to weep out.

I intend to do a proper investigation and find the faulty part, but in the meantime with a depressurized system, what should I consider replacing DIY?

I figured the two schrader valves and the orifice tube at minimum.

Of course the receiver/dryer will be replaced when the system is finally put back together.

I will be running R12, nothing else. This isnt a bozo request of help me fix my system. Im aware of the steps to repair it right, and Ill be sparing no expense at my shop of choice. But if there are some things I can do to be proactive on a 30yo car, I should.

Besides whatever o-rings I can access, and the orifice/valve inserts, should I replace anything else? If Im staying with R12, does it make sense to upgrade the condenser anyway?

Thanks!

rscurtis · #2 02-14-2013, 05:16 PM

I had a problem like this with my signature car. It would lose refrigerant during periods of non-use. One of the "O" rings on the expansion valve was cracked. As long as it was flooded with oil, it was OK. As soon as the oil was gone, the refrigerant would leak out.

You also get my vote on staying with R12.

JHZR2 · #3 02-14-2013, 05:26 PM

Well Ill hope that it was on the expansion valve here, since that is reasonably easy to access, as I understand it...

vstech · #4 02-15-2013, 09:20 AM

first thing I'd do is change the expansion valve, (you don't have an orifice tube) and pull the condenser, and clean it REALLY REALLY well and remove any dings it's got. (be careful removing the coil, the lines are likely rusted, and will require heat/penetrant to free) you will also need a new reciever, but DO NOT INSTALL IT! it is the LAST thing to go in before you are ready to evacuate and charge the system.
you might as well flush the lines, and coils so you have a clean system, and install fresh mineral oil in them.

Hit Man X · #5 02-15-2013, 11:15 AM

Not sure if the W123s received a condenser upgrade for the '85 MY or not, but the W126s did... it should be something to investigate. OR just go for a parallel flow. Not sure how hot it becomes there, but here in the south we need all the help we can receive.

Brackets are available for a Sanden conversion also to get away from that garbage R4 compressor. A cat here makes them, Klima Kit, and European Cooler Air in Dallas. Another thing to think about too.

My Sanden conversion is still working fantastic a year later. Best thing I ever did for my 300SD

JHZR2 · #6 02-15-2013, 12:51 PM

yeah the sanden is a lot of custom work and cost, my R4s have worked good enough for years...

But the condenser is something to investigate... Ill look into that.

Would a parallel unit do much for me with R12? Would it allow me to have more refrigerant in the system?

Thanks!

BillGrissom · #7 02-15-2013, 04:55 PM

R-12 is extremely expensive now. I have used butane mixtures in my old cars for 10 years, with no problems, Dura-cool but many other brands. It is compatible with R-12 oil and works slightly better as a refrigerant. You can read many strange rants about it. The EPA opposed it for years, out of supposed safety concerns (isn't that NTSA's job?). They bizarrely decided the only legal path is to first convert to R-134A, then butane. Yes, hydrocarbons are flammable, but so is Freon and R-134A. Indeed, the later forms poisonous phosgene gas when it burns. They put mercaptin in the butane's so you would smell a leak, and you don't put in hardly any (can feels empty).

BTW, the EPA is outlawing R-134A because it is a potent green-house gas. Not sure what they say about the "ozone hole" now. The deformed frogs in Costa Rica turned out to be due to a bacteria (not uV radiation) and there have always been 3-legged ones around.

Hit Man X · #8 02-15-2013, 04:59 PM

$10/lb for R12 is expensive? My 30lb tank was $300 early fall. 12oz cans tend to be $15-30 in the summer.

JHZR2 · #9 02-15-2013, 05:10 PM

Yeah, R-12 has come way down in recent years...

rscurtis · #10 02-15-2013, 05:31 PM

IMO, the changes in refrigerants over the years has nothing to do with the environment. It has to do with manufacturers lobbying the government for patent protection and the subsequent royalties on new products.

Don't believe everything you see on the internet, and believe very little of what Big Government tells you.

ROLLGUY · #11 02-16-2013, 11:45 AM

Quote:

Originally Posted by rscurtis

Don't believe everything you see on the internet, and believe very little of what Big Government tells you.

AGREED!

Graham · #12 02-16-2013, 12:23 PM

Quote:

Originally Posted by rscurtis

IMO, the changes in refrigerants over the years has nothing to do with the environment. It has to do with manufacturers lobbying the government for patent protection and the subsequent royalties on new products.

Don't believe everything you see on the internet, and believe very little of what Big Government tells you.

This is a very good example

JHZR2 · #13 02-16-2013, 12:42 PM

Not sure why this is diverging into a politicing over R12... There are enough other threads to discuss that stuff. My system was designed for R-12, and it is cheap enough and Im willing to pay even if it wasnt, for the right stuff to be used. Im not putting some hydrocarbon in there, not am I intending to fill with 134a.

All this is about is what I can do to be proactive on a 30 year old AC system which obviously was tight for years and an extended sitting period caused it to leak out. Just trying to capitalize on the lack of refrigerant in there to do as much as I can.

BTW, I have my 608/609 license, and may consider doing this repair correctly myself instead. Good excuse since there is nothing to recapture prior to starting, unless I use a nitorgen/R22 mix for troubleshooting.

So it may be good time to invest in a decent size bottle of R-12. Where can I get the best deal?

Hit Man X · #14 02-18-2013, 11:26 AM

Check CL or similar for the large capacity tanks or the 12 packs. Time to jump is now, it is cold out and demand is low... just like if you were in the market for a convertible or a boat.

A parallel flow will not add capacity, just the ability to dissipate heat quicker. I would do this for sure on an early car, regardless of what compressor you opt to utilize.

It has been over a decade since I owned a W123, so my memory is not great on them. I do recall them having a smaller aux fan too. A more efficient one that moves more air could be smart also.

Graplr · #15 02-18-2013, 06:01 PM

If you are using R12, I wouldn't bother with a parallel flow condenser. On my 84 SD, I installed one planning on using R134a. I can't recall my exact results now I believe I was getting in the mid 40s. I changed it out for R12. Slight improvement. Not enough to justify switching to a PFC IMO.

Only reason I switched was that my old condenser had a leak so I needed a new one anyways and the costs with new fittings on the PFC was comparable. Also I was planning on using R134a. Since you don't need a new condenser and are using R12 I'd stick with the regular one.