jwfisher3

Anyone done a R134a A/C conversion? My '86 300E is starting to blow luke-cool air, which I suspect means that I've got a slowly evacuating system. Since R-12 is now an illicit substance, I thought to convert to R-134a. My brother-in-law tells me that it's a simple matter of totally evacuating the system and replacing a couple of fittings, all for ~ $30. Not that I don't believe him, but it sounds suspiciously easy, and if that were so, wouldn't everyone have converted by now?

Any info would be appreciated.

worleydave

Actually had this done to my old '88 model 735i. Had it done at a Porsche independent shop for around $200. I don't know what all the procedures entail, but I think the new refrigerant runs at higher pressures than R12. If you are loosing coolant, you may want to track that down first. A coolant leak is a colant leak, and you can imagine it would be worse at higher pressures. Although, 134 is a lot cheaper to **** away than R-12.

RUSSH

That really is all it takes. I guess a lot of people don't realize how easy it is.

shertz

I had a conversion done today on my 92 300E. The mechanic removed the dryer i think it is called, sucked the r-12 out, put oil and 134a in. Reason i finally did the conversion was that i have a slow leak and this year i couldn't find a place with r-12. They tell me (part shops) that it would be 95.00 a lb. if they had it. So far so good works well and now at least if it leaks, i can get more.

BTW with the dryer it ran 225.00.

pkmaven

To convert from R12 requires a new receiver/drier (not expensive) and a competent tech who knows about the incompatability of these two refrigerants. Your Nippondenso compressor contains mineral oil which you cannot completely remove by evacuating the system. O-rings must be changed and a thorough cleaning of your system must be done to prevent breakdown because of incompatibility. The truth is that R12 is vastly superior in terms of cooling off a hot interior faster and producing colder temperature. Now that scientists are certain that the increased temperature of the sun is the cause of the hole in the ozone layer and not R12 we will all wonder about R134. Millions of wildebeast in Africa emit huge amounts of methane gas daily, so the amount of R12 is paltry by comparison. No new R12 is being manufactured but there are huge quantites of it around. Talk to a Mercedes dealer about what should be done to correctly convert, then you'll know if you have it done elsewhere. P.

rexdog29

Changed out my R12 last year to R134 on my 1992 300E and it cost me a total of $60 bucks. A new fitting adapter, 3 cans of freon, evacuating system, a little r134 freon o ring oil. No new drier. If you don't live in Houston, Tx. where it gets to almost a 100 deg. then go the cheaper way. The cooling is okay during the day and good at night. I kinda want to go back to R12 as i remember it was colder. Also, some people told me that 300E's 86-90 compressors were not very efficient with R134 and longterm not good. Check mercedesshop.com and do the search for a/c con. as there is a bunch of people who did theirs.

Sonny,

scottx

I live in San Antonio, TX and it's 100 outside. I am frozen cold in my 190e with 134a. All I did was vacuum it empty, replace the fitting's and fill it with some synthetic r134a & oil. I know the cabin is smaller but still.

It's so cold in that car sitting in downtown traffic at 4PM that I must turn it down. I should take a picture of an inside thermometer next to the outside temp gauge and post it

ps2cho

^ Not a wise decision...You now have both synthetic and mineral oil in the system. I suspect your compressor will not last long.

scottx

It was completely empty and we vacuumed it down. It's setup perfect now. This was all done by me and a good friend who does a/c work for a living.

We recharged it this morning just to vacuum it down and redo it. It wasn't leaking or anything. Work's so good.

ps2cho

The oil does not get vacuumed out, that is what I am getting at. You now have mixed two different types of oil, for twice the recommended capacity...

2PHAST

All Mercedes models (except W201) received R134a staring in 1992. What is the build date of your particular car? I suspect it probably is a very, very early 92 if it had R12 in it.

Marb

Im i. Houston as well and trying to figure out this ac thing can you please help?