81 240D Air Conditioning
 

My 240D has non-functional A/C. The Mercedes mechanic around the corner said the compressor and dryer need to be replaced, and maybe the hoses while he's at it. And it needs to be converted from R12 to a newer coolant. His estimate is astronomical.

I can get the parts at a reasonable price online with with the help of a friend can install them all.

Before I start ordering parts and replacing the current system I was looking for some advice on the conversion on whether I should do that. The kit online is about $20 and looks like a bunch of gaskets.

Is there anything I need to be worried about, should avoid, or should be thinking about? Any general information on the A/C system would also be welcome.

My car was converted by the PO. If you can stay with R-12, do so.

I also have an 81 240D. My A/C is non functional due to a siezed compressor amongst other things. Everything I've heard and read recommends against converting from R12 to R134. These older systems are marginal at best and they will not work as well after a conversion. If it were my time and money I'd stay far away from anyone who wanted to convert it.

- Peter.

I upgraded the A/C in my ’82 240D. I replaced the compressor, receiver dryer and expansion valve. Did the best job I could and then had my local M/B mechanic, vacuum the system, leak test it and charge it. Works well enough. Not as cold as the original R12. But not bad either. Did that 4 years ago and never had a problem.

Thanks very much,

Zill.

Everything I've read says stay away from R134a if you want to be cold.. I'm going with one of the alternatives in mine. Hopefully, I can get it done this weekend. I'll post how it goes..

I tried R-134a in mine for a while, it was cool, but not really cold, OK up to about 90F ambient. I went back to R-12, it's much better. There is no reason to use anything other than R-12 in these systems.

The "conversion kit" you see online is orings and replacement fittings. You can usually get them locally if you are going to use r-134 cheaper, since every LAPS has r-134 stuff on sale right now. I replaced my compressor with a reman unit from advance auto parts, ordered an expansion valve and a dryer from the parts place here (top of this page) and used an a/c oring kit from advance to replace every oring on every fitting I broke into. My car has a slight charge of r-12 left in it when i started, just enough to go fffft when i pressed the schrader valve. I took it to a local sho, who pulled a vaccum for an hour, it held, did a second hour, then I charged with freeze-12 from Diesel Giant. Russell has a wealth of info on his page. I looked at the cost of r-12, the lack of performance of r-134, and settled on freeze-12 based on russell's reccommendation. I haven't been sorry, works good here, even in the summer heat. It's been a year, still works GREAT. Chuck

Well, I'll add a couple of things to the discussion.
R-134A will work fine in these cars if you replace the stock condenser with a parallel flow type. The condenser is what keeps the stock setup from working as well with R-134A.
Freeze12 and R-134A don't seem to function any differently in these cars with the stock system. Both will cool the car pretty well. However, R-12 really seperates itself when the temp is above 95 from Freeze12 and R-134A. And Freeze12 also seems to run at higher pressures, pretty much a mirror of R-134A.
Take this into account: My wagon had reman compressor, new rec/dryer and exp. valve, system completely flushed with new orings/Nylog. It couldn't get vent temps below 55 or so when the temp was over 95 degrees, which it pretty much was ALL last summer. :sunny: Also, with the temp in the 70's and 80's here recently, it does get down into the mid,high 40's at the vents, but it doesn't do it as fast as the 240 on R-12, and the 240 gets down to 40-41.
This is First Hand info.......

That's great Zill, if we knew where you are this info may be useful. Maybe you can go visit the USER CP section and put that info in your profile??

It the compressor needs to be replaced it has more than likely experienced the "Black Death". In this case the whole system needs to be flushed out real good.
Then the compressor, receiver/dryer and expansion valve need to be replaced.
Nylog on the o-rings is a good idea.
Oil as needed and pull the system in a vacuum. If it holds then it can be charged.
If it doesn't hold vacuum all leaks need to be fixed until it does.
After you leak check and it holds vacuum run the vacuum pump for a minimum of 1 hour.

This is an easy process but it needs to be done right the first time. If you try to cut corners you will be doing it again.


Also, stick with R-12

Danny

Based on what everyone is saying it sounds like I need to replace as much as I can, make sure the system holds vacuum, and stick with R-12 if I possibly can.

Any easy way to flush/clean the system? The AC hasn't been used in about 10 years so I'm guessing the coolant has long since evaporated.

Just want to avoid having to tear things apart twice.

can you still buy r-12 ? where to get it ?

You have to a license to get it. MACS is a great way to go and get it.

what's MACS ?

Here is the link to MACS. They have taken over from IMACA for getting the EPA 609 license that is required to purchase R-12. http://www.macsw.org/imaca.php

I converted my 83-300D to Freeze 12 a couple of years ago. I am also running it in my Suburban. Here is my 2 cents. If you can, leave your system as R-12. That what is was designed for. Any replacement compressor you buy will be warrantied for R12 or R-134a. It most likely will not be warrantied for any of the other EPA (SNAP) approved R-12 replacements. R12 costs about $65.00 a pound and your system need a little less then 2 lbs. (This is from memory but it's in the ball park.) However, even if you spent the time to get the license, by all of the tools such as a vacuum pump and guages, you will have a very hard time finding the R12 in 1 lb cans. A 20lb jug will cost you about $1200.

You should always replace your receiver/drier when you replace your compressor. There is a dessicant in the can the absorbs moisture and some times a filter. Not only is this good practice but you compressor warranty will be voided if you don't.

The Freeze 12 is an option I went with because I decided to get the license and invest in the tools. Freeze 12 is compatible with R12 refridgerant oil so I don't have worry about left over oil in the system being incompatible with the Freeze 12 oil. With R-134a the oil used in the R12 is not compatible with R134a and will gum up system if it is not properly flushed.

R-134a is a smaller molecule then R12 and requires the original A/C hoses to be replaced with a barrier type A/C hose. Otherwise the R134a will leak out over short period of time. Freeze 12 is a large molecule and will not leak through the orginal R12 hoses if they are still in good condition.

You can find more information on Freeze 12 at www.freeze12.com . I still recommend staying with the R12.

TimK