AC Expansion valve?

[cam76034]

Put my gauges on the 91 yesterday. Static pressure was about 35, but with ac compressor on, it went into vacuum, pegged below 0. From what little I've gathered on the web, it sounds like a faulty expansion valve. Anybody else replaced this ? it looks like a real PITA.

[XM_Rocks]

Put my gauges on the 91 yesterday. Static pressure was about 35, but with ac compressor on, it went into vacuum, pegged below 0. From what little I've gathered on the web, it sounds like a faulty expansion valve. Anybody else replaced this ? it looks like a real PITA.

Shot you a PM about the shop manual.

Let me know if I can help in anyway.

[cam76034]

Hopefully the r12 and r134 systems are pretty much the same.

[Walsted]

If I am reading these charts correctly, (http://www.chillers.com/PT%20charts%...frigerants.htm, http://home.earthlink.net/~bob1.gard...essuretemp.pdf, and http://www.aircondition.com/pressure.htm), the 35psi static seems low unless you checked the pressure with the outside air temp in the low 40s.

I did the R12 to R134 refridgerant swap on a previous (non mazda) vehicle (since R12 prices are outrageous), and the R12 system worked on that vehicle with R134a refrigerant, but not quite as well as I would have liked. I also did it wrong a couple of times before I did it right, and managed to get a compressor to eat itself by using the wrong lube oil. When I finally did it right, I cleaned the old expansion valve instead of bothering with a new one, and things worked well enough for me.

Hope this helps.