dmorrison and engatwork reply...
Thanks for the tips. My system has been inoperable since last year. I don't know anything about zero pressure, but I turned the a/c off as soon as it stopped blowing cool.
Originally (before this all happened) my a/c friend was in my car and noticed the compressor was cutting in and off, so he tested the pressure and subsequently replaced the "evaporator valve/unit" that's just behind the glovebox because the hi/low pressure was off and found this valve was blocked. He then recharged the system, still r12 at the time, checked the pressure and it was fine. But it still wasn't blowing cool enough, routinely the compressor cut off before it got cool, eventually cutting in, consistently. We both had to leave, frustrated.
Here's what happened next: I had stopped for fuel on my way home (40 miles), when I started back on the freeway I immediately noticed it wasn't blowing cool anymore and turned it off (since it was simply blowing-in the outside 100 degree air).
Unfortunately my friend soon moved even farther away, then the weather got cooler, etc, etc, etc.
I would love to be able to figure this out myself. I'm mechanically inclined but not familiar with A/C so I accept my friend's benevolence (and 1-1/2 hour drive ea. way). I'm also devoted to my car, but when it's hot outside I'm forced to drive a "tin-can w/air."
Not to mention- opening the windows at 70 mph may eventually damage my 240's perfect headliner.
BTW how much should I expect to pay for R12 now?
And how do you suggest I go about finding a reliable, reputable a/c shop? (since I don't know what to look for or look out for?)
Thanks everyone. I wish I knew about this site a year ago. Oh well...better late than never.