AC Repair - PeachParts Mercedes-Benz Forum

dagObx · #1 07-26-2009, 03:08 PM

Since I smashed up the front end of my '87 300D, I'm looking at having to replace the AC condenser, drier, etc. It has been converted to R134a by the previous owner(s) & I am thinking about putting it back to R12 standards & using one of the "replacement" R12 products. The R134a ain't cutting it....

Any advise as to how I can do this without spending a fortune? I tried a search on this & didn't come up with what I needed.

Thanks for any input!

leathermang · #2 07-26-2009, 04:23 PM

What do you consider ' a fortune' ?

How long does it need to work well for you to consider it a success ?

If 134a is not working for you ... why do you think one of the non R12 refrigerants WOULD work ?

What are these other refrigerants with " R12 standards " ?

#3 07-26-2009, 04:35 PM

I just can't fathom why you would go back to R12, THEN use an R12 replacement. I can't think of one single reason to do that. With the demand for R12 going down, R12 can be had for very little more money than 134 or a junk replacement. If you get lucky, you might even get R12 for less than what some sources are getting for 134 these days.

leathermang · #4 07-26-2009, 11:32 PM

Larry , the way I read his post was that the PO had 134a in it... he crashed it and is going to put something other than REAL R12 ....thinking that because some of these other refrigerants place the number 12 into their name..... or use the word ' FREEZE' to promote an image of something they are not...
So he is going straight from 134a to some blend or HFC....
Unless you can shame him into doing the smart thing...

dagObx · #5 07-27-2009, 01:24 PM

Hey, shame me if that's what it takes

. I'm just looking for options since the 134a hasn't been doing that good of a job - in my opinion.

I realize the AC in these cars aren't the best in the world. It won't freeze you out like most American vehicles will. But it would be nice to have a system that would cool things down in something less that 8-10 miles of driving in 85*+ weather.

I am relatively sure there is a leak in the system somewhere. Unfortunately I am not handy & have to rely on my local mechanic, who learned his trade at an MB dealership. He has been very informative & is reasonably priced, which has been a life saver since I'm lost once I get past changing the oil (which I do).

So, OK, lay it on me.......tell me what I need to hear.

Ken300D · #6 07-28-2009, 04:11 PM

To revert back to R-12 you need to thoroughly flush out the oil in the system and reload the system with R-12 and the proper oil for R-12. The oils used in R-12 and R-134a are not compatible with each other's refrigerants.

Don't flush the compressor with flush - instead run a lot of mineral oil through it, as mineral oil is the R-12 lubricant. The rest of the system you can flush with flush solution from a flush gun or with a compressed air supply.

My suggestion is that if you determine the compressor used in the R-134a retrofit is a "Four Seasons" compressor - just go ahead and replace the compressor now during the rest of your work. You'll get a better compressor and won't have to clean out the R-134a oil (PAG Oil I think) from it.

Ken300D

kingdoc1 · #7 07-28-2009, 04:46 PM

Sorry your car got damaged, but it sounds like it might be a somewhat fortunate thing, presenting the opportunity to really fix your a/c system.

The reason you are dissatisfied with the past performance of your system is simply because R134A is not the proper refrigerant for your system's design parameters. In other words, your system was designed for R12, and until you put R12 in it, it's not going to function to it's designed potential.

Don't waste your time and money experimenting with "substitute" refrigerants when you can just put the proper refrigerant in it and solve your cooling problems. Don't be fooled by substitutes that have "12" in their name, you need the original, the only, R12.

dagObx · #8 07-28-2009, 08:17 PM

KingDoc1 - you are exactly right: 134a was NOT meant for my car. I agree 100% that the system should be R12. I checked out FleaBay & found serveral sources for R12, plus I have a friend in the HVAC business who could purchase it for me.

Ken300D - thanks for the advice & how-to instructions. My HVAC buddy pretty much described the same process when we discussed my situation.

So, you guys have convinced me to go back to R12 - so that's what I will do.

Many Thanks!!! This forum ROCKS!!

leathermang · #9 07-29-2009, 12:48 PM

We have written a lot of stuff on this particular changeover .... I do not have a good thread in mind that I can refer you to..
but
WHunter probably does in his accumlated list of good threads...

Phil · #10 07-29-2009, 04:09 PM

The original system was designed to run R12. R134A is not as efficent so it would need a bigger system to get the same cooling as the R12 system so yes go back to R12. R12 has some environmental conditions so do it right and as others said replace the compressor and pressure check the system before you load it with the R12.

okyoureabeast · #11 07-29-2009, 04:30 PM

http://www.dieselgiant.com/repairyourac.htm

He's an excellent source for many maintenance type of questions. Hopefully his pictorial will be of some use to you.

zeke · #12 07-29-2009, 05:20 PM

Quote:

Originally Posted by LarryBible

I just can't fathom why you would go back to R12, THEN use an R12 replacement. I can't think of one single reason to do that. With the demand for R12 going down, R12 can be had for very little more money than 134 or a junk replacement. If you get lucky, you might even get R12 for less than what some sources are getting for 134 these days.

Larry, I see you saying this in a number of posts, but I just don't get it.

I recently went shopping for R12. Best I could find was on ebay (shady - never know exactly what you will get) for $30-40/lb. I found some 30lb cylinders on ebay for ~$300, but shipping was a problem as R12 in that quantity is considered hazmat, and major shippers charge a fortune to ship it.

So for $30-40/lb for a sealed original can, how is it you can say that $90 for a charge is too much? 2.6 lb x $30 = $78, but that doesn't include shipping.

I would love you to PM me with you secret sources!

#13 07-29-2009, 06:15 PM

http://cgi.ebay.com/ebaymotors/FREON-DUPONT-R12-R-12-2-12-oz-CANS-100-New-Freon-NR_W0QQcmdZViewItemQQ_trksidZp3286Q2ec0Q2em14QQhashZitem3354395d04QQitemZ220456377604QQptZMotorsQ5fC arQ5fTruckQ5fPartsQ5fAccessories

This was the very first one I came to. Shipping has never been a problem in the past. The only "problem" is having a 609 license to legally purchase it. There are numerous sites where you can go and for $20 take an open book, online test and have the license.

47dodge · #14 07-29-2009, 06:21 PM

Has anyone tryed "enviro-safe R-12a" It is a hydrocarbon refridgerant. I am going to try it. My system is empty, no idea what was in it. So flushing, and a new compressor, filter dryer, are in order anyway. The old compressor is locked up. Does anyone know which relay is for the compressor clutch? It is stuck in the on position. Or at least appears to be, as there is power to the clutch at all times.

dagObx · #15 07-29-2009, 09:33 PM

Quote:

Originally Posted by Phil

.......and as others said replace the compressor and pressure check the system before you load it with the R12.

Phil, there was no mention of replacing the compressor in any answer other than yours. Is this something I MUST do? They seem quite pricey, at least as far as I have seen.