I'm struggling with the results of the R134a conversion on our 1989 300TE (done late last summer, seemed to work OK). The mono valve diaphragm and plunger look OK. Tonight I am going to clamp the hoses to/from it to see if that helps get the car cooler, both to certify the mono valve is OK and maybe to get some insight on whether the control panel might be causing some problems.

ANYWAY, I'm really wanting to go back to the dealer in Knoxville who convinced me to do the conversion when we had a new AC hose/manifold installed to put it back to R12. I've seen some comments, from the renowned stevebfl especially, that it is not recommended to convert a pre-1990 model year W124 to R134a.

My question - are there differences between the AC systems before and after 1990 that make post-1990 more amenable to the conversion? I noticed on a neighbor's 1995, for example, that it had two auxiliary fans, our 300TE has only one IIRC. Compressor output? Evaporator size?

Wondering if there are some components to change which would still be fairly economical in the face of going back to expensive R12.

MANY MANY THANKS FOR THE ADVICE -

Sweating in Indiana,

Brian
89 300TE 165,xxx poor A/C
84 733i 5-speed 150,xxx very poor A/C