I've always wondered why you just can't get a condenser off of a 1995 E300/320 and install in the earlier models and go with r134a. If you are replacing the heater coil I would also recommend replacing the evap and all of the vacuum pods that are in the dash.

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Jim

I don't think you have to go any deeper to replace the evaporator than the heater core; they are exactly the same job. And it's a big job, most folks here report ~20 hours of labor.

The evap used to be $200; I would expect it's gone up in the few years since I last looked at the price. Get one with a pre-installed expansion valve; you need to change it anyways and this will save you some time/trouble/effort.

Replace every o-ring in the system while you have it open. Brittle old o-rings are a common source of leaks.

The connections are not the same, so you'd need to do some custom hose work to get it plumbed. I also think the dual electric fans with the shroud are equally important to get good low speed cooling.

Ironically the later 124 cars that came with R-134a from the factory have among the better a/c systems I've experienced; they really make a lot of cold air, even a idle on a 100F day.

I agree with keeping the R12 system. This is how the car was designed.

Since you are changing the evaporator, you should change the expansion valve too, as the two are connected. If you didnīt want to change the evaporator, then you could always flush it out. Since the system has been open for a long time, you should flush the condenser too.

As long as everything is open, change the seals as well.

R12 must use mineral oil where 134 uses PAG oil.

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