Expansion Valve problem?
 

OK, I know it's the wrong season to be asking these questions for most of you, but I suspect that my AC expansion valve has died and I'd just like to be sure before I rip it out. This doesn't look like being fun, especially as I will be doing it next weekend when the temperature is forecast to be 41*C here.

My AC is fully charged and runs cool initially, but within a minute or so, it stops running cold. The AC guy says the compressor is compressing and everything else looks OK. It had a new filter/drier fitted only a couple of thousand miles ago.
Mechanic reckons the expansion valve "could" be the problem.

I don't know which pipe goes where, but pipe A is ambient temp and pipe B is cool (not cold). I think this whole valve should be really cold when it is working correctly, yes?

So what's the consensus? Dead valve?

A few pics ...
http://forums.pelicanparts.com/uploa...1266829505.jpg

http://forums.pelicanparts.com/uploa...1266829608.jpg

if the expansion valve (EV) is bad, the pressures should show it. the low side will be too high. you could also have too much refridgerant in it.

when my EV went bad on my truck, it was like the compressor was not working, hi side was low and low side was hi.

if there is moisture in the system, it will freeze up at the expansion valve. Depending on how much time you want to invest, the system can be evacuated, drier replaced, but if you're going that far, the expansion valve isn't much more work or cost.

what are the high and low side pressures?

The pressure ratio (high side v/s low side) should be about 10:1 @ 2K rpm's.

Give please us more data on the H/L sides before and after the A/C degrades.

Our '86 runs about 24-240/260 on a 70 degree days @ 2K rpm's.

System evacuation/vaccum check would be my first step.

Also, there is a forum member (Kruell)? who has posted a few very credible A/C threads.

Good luck,

Gerry