now i know why everybody here is so hip to doing all their work themselves.

i recently had my compressor replaced and they decided to convert me to R134 while they were at it, which i just realized. i really wouldnt mind if i thought it cooled just as well, but i noticed that the ac didnt cool as well as i expected BEFORE i knew it was converted, so i dont think its in my head. they did the conversion right, replaced the drier and all that, but i really dont think its the same.

i have a really good relationship with this place, so i know they would switch it back at no charge (they better, especially since i havent paid the bill yet!) but im wondering how long it would take and what they would have to do. is it really worth it? would it be almost the same or would i be dissappointed with the switch back to R12? they wouldnt have to get a different compressor would they? are there any advantages to having R134, any reason to keep it since i already have it?

someday, when i have the time, space, and tools to do all the work myself, i will. until then, i have to deal with shops.

thanks

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1991 300 D 2.5 Turbo, 220k
also in the family:
1981 240 D 185k
1991 350 SD 185k
2006 S 500
2005 SLK 350

There are a lot of threads on the use of R-134 vs. R-12.

Larry wrote many of them.

In a nutshell, it's not a good idea to use R-134 in a system designed for R-12. Not only does the cooling capability suffer, but the pressures are significantly higher and the compressor takes more abuse. The longevity of the system is affected.

The entire reason to switch to R-134 was due to the cost and unavailability of R-12. Larry recently bought R-12 for under $15.00 per pound. R-134 is close to this price now.

So, there is no good reason to use R-134. There is no good reason to keep it, even if you already have it. However, a thorough flush of the system must be done, prior to introduction of the new R-12. It's quite a big task. The danger lies in the fact that they will probably cut corners, drastically, because they are not getting paid a dime for the switch.

In fact, I'm thinking about doing a reverse conversion back to R-12 on the SDL, if I can get sufficient knowledge and tools.

The 124 car is one of the worst examples for conversion to 134. It's condensor is just not adequate for the conversion ESPECIALLY in Houston! There aren't too many places that demand top a/c performance more than Houston.

As Brian said, there is just no reason to do this today. If they did this without your permission, you have all the right in the world to be HIGHLY upset.

Changing to 12 might be simple depending on the oil they used. It MUST be an oil that is compatible with R12 or more damage might result than if you left it 134.

Best of luck,

In the past I've read on this forum of bad experiences switching to R-134, but from personal experience have had very good luck. I have converted two late eighties Fords, a Mercedes W123, and an aftermarket A/C kit. They have all been running for 3 to 4 summers with no problems. I changed the o-rings, pressure switch, and accumulator/drier in all, the compressor on one Ford and the Mercedes, and the expansion valve on the Mercedes. I used the recommended oil for R-12/R-134 compatibility and filled the system to approximately 85% of the R-12 charge.

One Ford is my sister's, and she claims it is just as cold as with R-12. I checked the Mercedes, and the air outlet temperature in the center vent was only a couple degrees higher than factory specs, and it can freeze you out most times. The only times it will not freeze you out is on extremely hot days, around 100, but still does a very good job of cooling. The aftermarket kit was pretty much a quicky job, but nothing has failed in the system yet.

The main reason to switch to R-134 is price, though it is getting high too for some reason. If they did it right, I don't know why you shouldn't leave it in there. Try it for a few days, and if you don't like it (which sounds like is the case already), have them switch it back. Just make sure you tell them this up front. They were probably just trying to do you a favor by switching, as the system was being repaired anyway. Plus you should have a warranty on parts and labor for a while. I bet they will charge you for the R-12 freon, or at least the difference in price.

One thing to check is that the auxilliary fan is working properly and is actually running. Had a service guy tell me once that cars with the electric fan take better to the retrofit than without. This most likely is due to cooling of the R-134 in the condenser as much as possible to increase efficiency.

I would be royally bent out of shape if it happened to me...I would have demanded they put it back to original...which is R12 at no extra charge...since you were not asked to approve the conversion...

__________________
Proud owner of ....
1971 280SE W108
1979 300SD W116
1983 300D W123
1975 Ironhead Sportster chopper
1987 GMC 3/4 ton 4X4 Diesel
1989 Honda Civic (Heavily modified)
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Section 609 MVAC Certified
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"He who fights with monsters might take care lest he thereby become a monster. And if you gaze for long into an abyss, the abyss gazes also into you." - Friedrich Nietzsche

Brian laid out the facts.... I am amazed they would change over in Houston in the first place...but WITHOUT your permission ?!?.... truely amazing...

Since for some reason you choose not to put your location in your profile I have no idea where you live, but I fully expect that you don't live in Houston, Texas or a similarly hot, muggy climate, if another exists.

He already has "tried it" and it is not cooling as well as it did when working before.

Have a great day,

In addition to what Larry said..... those Fords were probably not the Delco R4... which certainly seems to be less able to survive abuse than later ' normal ' type compressors ( not scotchyoke )....

I know for a fact that some shops these days are doing this unauthorized conversion, better check your adapter ports and freon to be sure after taking your car in for any a/c service/recharge. Trust me, this is happening more often than you may realize, maybe because of the price & limited availability of R12, some shops dont even have the equipment to service R12 anymore, seems like all these R12 equipment is for sale on ebay.

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benzino