More AC Questions

[Keyav8r]

The AC in my 91 Eliminator worked well last year. Over the fall & winter it was laid up while I did some floor repair, cleaned the interior plastics, cleaned and dyed the carpet, etc. Fired it up this spring and everything that worked before the lay-up still works - with the exception of the AC. The compressor turns (clutch engages and compressor turns when the upper control is moved to Normal or Max) but it only blows ambient temperature air, about the same temperature as in Vent. The hot/cold door in the plenum works (cable operated) as I can see the arm move when I move the lower control lever from cold to hot to cold and the temperature of the air changes (hot air in hot/cool air in cold). The upper control also changes the air flow as designed (air through defroster when in defrost, floor in heat, floor, floor and vents in bilevel, vents in vent, and vents in normal or max). Also, the recirculation door opens in max (vacuum operated).

The truck has R134a fittings on the ports and appears to have been converted but I can't confirm that 100%. I've ordered adapters (R134a to 1/4") to hook up AC gauges and check low and high side pressures. Low side was around 25-30 PSI according to the gauge on a R134a recharge can. The system took a couple of shots from the can and pumped back down to around 45 PSI suction and holding. No apparent effect on cooling.

Any suggestions from the AC gurus on what I should try before my adapters get here?

[Keyav8r]

After reading a little in my service manual (when all else fails read the instructions), I hooked up my AC gauges with the R134 to 1/4 adapters and opened the service valves to the mid point and discovered I had a low charge. With the compressor running I had 0 on the suction side and 50 PSI on the discharge side. I blew most of a 20 oz. can of R134 into the system and never got the high side above 70-75 PSI while charging. When I stopped charging the high side gauge would start dropping back towards 50 PSI.

Should I assume that:

(a) I have a big leak somewhere, or

(b) my compressor is bad, or

© both of the above?

Unless someone out there has a magic bullet, I'm looking for a good auto AC shop around Birmingham to help me determine how much of my life savings it will take to make my truck blow cold air, like it did last summer.

[Keyav8r]

The system does strange things with a simple a-b-c list.