Expansion valve - R12 v R134A
 

I notice that the new evaporators come with expansion valves that are labeled R134A.

I've seen it said on the forum that it doesn't matter, that the ones marked R134A work just fine with R12.

When I replaced the evaporator in my 1990 124 (R12 system) a couple of years ago, I used the included expansion valve, which was labeled R134A. It seemd to work fine.

Now I am replacing the evaporator in my 1991 124 (R12 system) and it has a R134A label on the expansion valve.

And today I noticed that the MB Electronic Parts Catalog lists two different part numbers...

R12 Expansion Valve = 201 830 06 84
R134A Expansion Valve = 201 830 04 84

Is there a difference after all?

Yes there's a difference..

One the reference freon is R-12 and one it is 134a. Makes a very small difference in the performance of the system. They can no-longer use R-12 in replacement parts so all the new ones are filled with R-134a.


Michael

The pressure at low temperatures is nearly the same between 12 and 134a. The difference really shows up on the high side.

You will be fine with a 134a-compatible TXV running R12.