Bad A/C Expansion Valve
 

now i know most of you, this will fly right over your head, but to those of you that know, today, i was at my buddies shop for a couple reasons, and we were checking my a/c lines to make sure the charge was holding good (holding for 2 weeks strong). we ran the low side pressure while the a/c and car were running, and it's hovering between 37 psi and 40 psi respectively. when letting it sit to cool down for an hour and a half in the shade, the high and lowside equal out (forget what the reading was) and when the car and a/c were running, i was getting a low reading of 200 psi at idle, 225 around 2,000 rpms on the high side. we were trying to eyeball what the ideal pressure for the high side would be at idle and at 2,000 rpms, but his service manual says NOTHING about spec pressure ranges. what if any information do you guys know? the idea is that we believe my expansion valve might be bad, as when the engine revs past 2,000 to 3,000, the pressure on the low side registers under 25 psi... doesn't this seem odd?
peace

cable, thanks for being the one to repsond, however, what is quoted IS the problem... anywhere above 2,000 (like 2,000 2,200) it starts dropping... and the air, i mean, the car gets cold, but the second you turn off the a/c, you start burning up... what would low psi STARTING at 2,000 psi mean? cause this is exactly what is leading him to believe my expansion valve has gone bad... and unfortunately, i have no idea what this fuckin thing is :(. ah... regardless, thanks a bunch man, i've gotta pick up a fuckin haynes.. NOBODY buy a chilton's manual (unless it's one of those 20 pound 'auto'-bibles)
peace