Haven't had AC most of the summer in my '00 V70. Finally started getting warm in the Northeast and I decided to start looking into why. Thought I might be low on 134a so picked up a refill kit with gauge and the low pressure line is between 90-100 psi. Yikes! Should be a lot lower right? Compressor never turns on so I though it was low on refrigerant but obviously something else is going on.

Worked fine last summer and only recent work was alternator replacement over the winter. Did a fair amount of reading and have seen references to bad Pressure switch which is located right near the low pressure line. Any other thoughts or input as to what might be wrong? I'm not getting any flashing lights when I engage the AC system as I've read about. Just hot air and I never feel the compressor turn on. I checked fuses but none seem to point specifically to the AC system ( I don't have an '00 manual). Any help would be greatly appreciated.

I would like to at least diagnose the problem myself so I don't get taken at the dealership. Thanks!

EDIT: My pressure switch doesn't have anything plugged into it...is that right? It's there, but looks like the picture below...

 

Tech never plugged in the lead to the pressure switch when they replaced my alternator. DUH! All that fuss for nothing. It was wrapped up and tucked away in a corner by the headlight where I didn't see it. just walked out the car, found it, plugged in and voila...Cold Air! Sweet!

 

Glad you found it!

 

Very similar situation to willysjeep here. Replaced alternator on my friends v70 yesterday, tried to use ac today for the first time this year (also new england) and what happens when we turn the ac on is that compressor kicks in just for a second and turns off. It will only do this when car is first started, later on it will not kick in at all. Gauge shows 90psi, danger zone. So i thought maybe its overcharged (doesnt make much sense since he didnt use ac since last year and it was fine back than), and tried to free some of the freon from the system. Nothing changed, ac not coming on. tech, where to start on this one?

 

Did you unplug the High pressure plug swapping the Alt?
Also did you pinch a wire?

 

1. no
2. no

 

Jump the low pressure switch and see if it comes on.
Does the cooling fan come on when you turn the A/C on?