My 1993 240 wagon AC's compressor does not kick on unless I bypass the high pressure switch. Then the AC feels great. Nice and cold.

When running, the freon pressure is about 35psi - pretty good.
If I quickly hook up high pressure switch, AC keeps working.

When not running, the pressure is 75psi. And of course, the HP switch doesn't let in come back on and I'm back to square one - need to bypass switch again.

My questions...
- Does it sound like a high pressure switch problem?
- Is 75psi for AC normal for car at rest?
- What are the concequences of permenently bypassing the HP switch?

Thanks

 

has that car been converted to R134a or is it still using R12 ?

I dunno off the top of my head what the pressure should be, but 75psi at rest sounds way too high.

 

R134a. Big yellow tag to tell me.

 

It sounds like the switch to me. The effect of having the clutch running the entire time will put more wear and tear on the clutch on the AC compressor, eventually crapping it out. But that will not happen for a little while if you just drive the car in the city. A new switch will cost you somewhere between $20-30, depinding if you want genuine Volvo or aftermarket.

 

was it last filled by a properly equipped AC shop, or by a driveway amateur?

 

Last filled by a pro about a year ago. Amateur (me) 2 days ago. Do you think it just needs an evacuation and fill?

 

was it doing this before you (re)filled it?

 

Yes. First thing I did was replace rocker switch and relay in dash. They seem to be working. That's when I started poking around under the hood including adding some freon.