Capt C.
 

I did my 300E at home so I KNOW the "painful" feeling. The bad news is that to removed the evaporator from your last picture, you have to remove the black box, which contains the evaporator and, to do this, the wiper assembly, blower and motor has to come off from the engine bay!
In the 300E, replacing the evaporator cost around $1500-2000. The evaporator cost around $200 the rest of the cost is labor.:(

I've never been one to shy away from tearing into a car but this job looks like a bit more than I'd care to do for fun.

Now that I know about the crash sensor placement, wouldn't it be wise to remove it rather than risk dropping a solid/heavy object on it? Sure would hate to be the guy to turn the key upon completion if the sensor got tagged :eek:.

Copper vs. aluminum condenser?
 

Someone mentioned in this thread changing out the condenser (not evaporator) to a copper one vs. the aluminum one.

Does this help with the lower cooling efficiency of R134a vs. R12?

I'm asking, because my 1988 300TE wagon was converted to R134a, but it doesn't blow as cold as my 1993 500E which has a different condenser and two aux. fans vs. the 1988's single aux. fan.

Thanks,
:-) neil

It is not just the condensor. The hoses are different diameters, the expansion valve is different, the compressor is different and the evaporator is different.

The conversion process works, but with limited results.

Now that's the "facts" I was looking for.

The A/C compressor is the stock R134a from the 1995 C36 engine. I've checked part numbers, and I've found differences between the R12 W124's and R134a W124 on the condenser, but not the evaporator. We did change out the expansion valve, but I'm not too sure about the hoses.

Donnie- do you think I would get better cooling if I change out the condenser, hoses, and go to dual aux. fans, (and changeout the PowerSteering cooling line as well)?

I'm not sure if the R134a evaporator now supercedes the R12 evaporator, if so, maybe I should change out that instead.

I've taken apart the ENTIRE dash and center unit to change out the HVAC vaccuum elements, so I can save some labor.

:-) neil
1988 360TE AMG
1993 500E

One more data point. I used the cryo-chem product on my 124 with leaking evaporator. It did an essentially perfect job of sealing the leak(s). Prior to treatment the car lost about 1lb of refrigerant/month. After treatment, I couldn't detect any leak over 10 months. Unfortunately, my compressor developed a shaft seal leak and seized at that point. Can't prove whether the failure was connected to the treatment or not. I'd guess not - I think the system was a bit overcharged, which will cause such a failure.

Probably the Cryo-chem caused
 

the compressor to seize! If there is a leak from the seal, they advise strongly NOT to use the product.

Of course, if you didn't have a compresor seal leak at the time you fixed the evaporator leakl, how could you know. About the only thing one can do is to flush the system after the leak seals with 'fresh' R-134a.

That brings up an interesting problem: I pretty sure that an A/C shop will not want to re-claim your 'dirty' R134a in their AC machine. So you would probably have to 'dump' it.