I believe, and I'm sure the other ac experts (vstech, air&road and others) agree:

The 123 was designed for R12. Putting other than R12 in results in the following:
- sub par cooling (I don't understand the exact physics but 134 can not move the heat as well as 12), and this leads to
- damaged components (high side pressure spikes in hot weather beyond design limits) I have read several stories of people suddenly venting their refrigerant in traffic when a hose or pressure switch or compressor seal lets go.

Besides being against the law and the green police, vented refrigerant is not good to breathe and I remember one guy getting the refrigerant and oil sucked in to the intake causing a temporary runaway condition.

Just my 2c worth, I'm a believer in R12 after vstech fixed my ac the right way.

I feel blessed to have my 134a converted 1982 300CD working great for at least 2 summers (the present one and the last) with very low vent temps (low 40's). I even have to turn the fan to low sometimes when I get too cold. It has been well over 100 degrees here in the desert of So. Cal. the past couple months. I think the trick is to have a completely clean system, and add the proper amount of refrigerant. On the coupe, I started with a good USED R4, and completely flushed the entire system with the good solvent. Checking for leaks is also critical. My A/C guy (has recycling/recharging equipment) has done many 'Benzs for me, and is getting good at them. I do all the mechanic work, and he just checks for leaks and recharges the systems for me (about $80 each car). I don't know why other folks are having so many problems with 134 conversions in their 123's, but mine seem to be working just fine. I need to use 134, as R12 is not very available here in CA (also very pricey!). So far, I have had great success. Wish my luck on my next job: 1984 300SD....Rich

wow, it's good to hear from someone that's had 134 successfully converted into a pre 84 123chassis!
keep in mind the cd has a smaller volume to cool, smaller windows, and fewer doors... likely you have the windows tinted and I bet the car is a light color. also, in the desert, you are not dealing with humidity... that's a HUGE heat load on a cooling system!
88F with 60% humidity is about 3 times the amount of heat as 100F in 10% humidity... that's a lot when often in TX or SC etc, it's 95+ with 90% humidity!!!
these cars all pull in air from outside! so it's OUTSIDE humidity that is being dealt with! even with the max cool setting, there is a large % of outside air flowing through the car...

WOW you are good! You must have cheated (looked at my signature). Yes the car is white, but no tinted windows. I do keep a windshield shade in place when the car is parked, and that helps the car cool quicker. I am basically a cheapskate, and don't want to pay for r12 if I don't have to. The 134a works so good, I see no reason to change. I am hoping the 126 will turn out as good. It HAS tinted windows, but is gray in color.

the 126 has fine cooling, I got good results with 134 in my 82 with stock condenser.
keep in mind the MASSIVE cleaning job I perform each year though.
an 84+ condenser will help cool the car even better.

Is the Compressorworks brand a remanufactured unit or new? I know I need to replace the compressor, but not sure which is the best one. I know I need to stay away from the Chinese copies, but what about Delphi? Chances are slim that I find a good used one like I did for my coupe. I have tried one from Kragen (now O'reileys), and it was junk right out of the box.

The one for the 123 is, as far as I can tell, a brand new build. I got mine from a chain auto parts store and they did not ask for a core.

I believe they purchased the design from Delco/Harrison and are building these in Dallas.

I decided to go with the Compressorworks unit from the 'Zone. $207 out the door. I got ready to install it, and read the instructions about adding oil and turning it 10 times. I assumed it would turn by hand. When I tried to turn it, it would not move at all. I finally got it to turn a little, but it made a scraping sound like a broken ring scoring a cylinder wall. I assumed it was bad, so I returned it, and got my money back. The next day I talked to my buddy at my local A/C shop, and he said "you can't turn a new R4 by hand, you need a special wrench". He said that is normal for the R4, and that there was nothing wrong with the new Compressorworks unit. I wish the instruction sticker on the back of the compressor would have said that the compressor will be very tight, and that that was normal (I would be driving with A/C by now!). I can't bring myself to go back to the Zone and get the R4 again. I decided I am now going to try to make a bracket to install a Sanden. I have had enough with this GM garbage!

nahh. you can turn a new CW R4 by hand, but you have to be VERY stingy with the oil in it.
if you put too much oil (more than an oz) and the oil will bind the pistons.
I like to dribble a small amount of oil in, then turn it a few times, then dribble some more in, and turn it another few times. then let it spill out. and spin it some more.
I've NEVER had a CW compressor give me problems turning by hand. (I'm pretty strong though...:D )

If that's the case, then I got a bad one "right out of the box". I totally understand the procedure, but this one was clearly bad right from the start (IMO). Either way, I am in the middle of fabricating a bracket for a Sanden. I have a core and a spare engine in my garage, so I can do a mock-up without crawling under the car. I just got back from P-A-P with a bracket and a good Sanden. I will start another thread with photos and specs. I found a good bracket and compressor on an '86 Mitsubishi pickup (Dodge Ram)....Rich

That's cool that you have an extra engine for mock-up :cool:

It was a MOFO figuring mine out with the engine in the car...

Sounds like all great minds think alike, I just got back from the JY where I too got a Sanden and a bracket. :)

Mine was off a RX7 and appeared to be an aftermarket one with the "generic" bracket like the York adapter ones. It was already removed, so I couldn't see how it was mounted. I'm going to try to see if I can fab something up that will let me shoehorn it in, but I'm kind of doubtful. The subframe supports on the inner fender well on the R107, plus the UCA brackets make it very, very tight. I had to eliminate the R4 completely because there was no possible way it would fit. I think my only hope now is to somehow mount it solid, tight to the engine and then figure out how I can use a tensioner for the belt - probably something like what the one on the original 380SL used.

The compressor was only $20 so I think it's worth playing with a bit. Unfortunately I don't have an extra engine, so I'm going to have to pull mine out sometime to do the experiment.

I'll watch for your thread.

I think someone suggested moving the PS pump down and placing the AC compressor in it's place. This would be workable on a 116, not sure about others...

I have not seen the Klima kit installed, so I am at a disadvantage. Is the bracket you got aluminum or steel? If steel, it would be much easier to fab something. Unfortunately, the one I got is aluminum. As far as mounting, it is much easier to mount it solid and use an adjustable idler.
I will start another thread, and let this one continue....Rich

I, for one, would be interested in learning more about this strategy. Any pictures around on how this was done?