I have an 1985 RX-7 GS with a Wynn's A/C system. Does anyone know if the low pressure cut-out switch located on the dryer has a shradder (sp?) valve between it and the rest of the system? I sure would hate to dump my R-12 in an attempt to replace the switch.

If you could post a pic of the dryer/switch combo I could tell you.



if it's anything like a GM dryer/switch, then yes, it does have a schrader on it.

Usually the ones that thread ONto something have a valve, and the ones that

thread INto something don't.





Raul

I hope it is like the GM. Here is a pic. Sorry so blurry.

No, that is a different style. And judging by where it is installed, you're

out of refrigerant anyway. That style reciever/dryer is in the High

pressure side of the system, so if that is a (LOW pressure= open) type

switch, the moment the compressor kicked on the pressure would rise.

Considering the expense of R12 refrigerant, it would probably cost less

to retrofit it to the more plentiful R134. I would recommend taking it

to an automotive air-conditioning shop and have them give you an estimate for repair in either direction.



Raul

on all of the fb's the schrader valves are on the compressor



mike

I think that it is there to protect the compressor in case of loss of refrigerant. It also may cycle the compressor if the heat loss through the radiator is too great and overcools the refrigerant.



I bought this car a couple of months ago and found that the connections to the switch had been jumpered. Sometimes you have to do that to get the compressor to run when you are charging the system. Didn't know if that was the reason or if the switch was bad.



Seems to be cooling fine but on a day long trip I could swear that the evaporator coil froze up. This was before I removed the jumper and it could be the cause.



If you are interested I have a couple of articles from ASHRAE (American Society of Heating, Refrigeration and Air-Conditioning Engineers) that talks about R-134a in an unconverted R-12 system. Basically states that mineral oil from the R-12 system does not need to be removed and does work well with R-134a. No need to add the esther oil. I believe that it states that you can add R-134a to a system already charged with R-12 to bring the charge up to spec. The only down side is that the capacity is reduced because of the size of the compressor.