Had my 89 2.8L firebird for about 3 years now. A/C worked just fine up until last year autumn. One day it started pouring in the afternoon (as it does every day here in south florida ) and I kicked on the defrost. I was using the air before the storm, but after the 20 minute downpour and everything was hot and sticky, I turned the A/C back on to find it just blew hot air. Been like htat ever since.

Is there a fuse besides one in the passenger fuse block?

Any ideas why it would just quit, (and while I'm using defrost?)

I'm not at all good with A/C, but I did check the pressure with one of those silly on can refill gauges and it read towards the red on the gauge (50psi or so if i remember right.)

Any pointers on troubleshooting or where to start?

For what its worth it used to make a noticeable dip in RPM and I could "hear" the A/C compressor while it was on. I get nothing like that now... Just a tiny dip in voltage due to the fan that disappears when the fan is off.

 

Check and see if your clutch is activating when you turn on the ac. If its not make sure all of the switchs and wires are ok.

If the clutch is activating, then you most likely have a bad compresser.

 

I see nothing at all move when I turn on the AC, all the wires are plugged in and everything.

 

2 quick things to check, 1 with the key on engine off, turn your ac on & put a screw drive against to ac compressor clutch, if you feel the clutch seems to pull the screw drives to it & the clutch isn't engaged, give it a tap on the front, if it engages then you'll need to set the air gap. if not, then #2, with the screw driver lightly tap on the low pressure switch, they go out alot, if the clutch kicks in, then the switch is bad, if not you can jumper across the low pressure switch & see if it engages, if it does check to see if the a/c is charged. if the a/c is charged the switch is bad. the low presuure switch in on the accumulator.

 

No, and No. clutch doesn't engage at all. Doesn't seem to pull the screwdriver to it at all. I tapped on the low pressure switch, and got nada.

 

Unplug the low pressure switch and jump it with a paper clip, then try again. If that doesnt work then check for voltage on that same plug. If theres voltage there than it's probably the compressor.

 

Should've thought to do that myself... <smacks forehead>
Will do so tonight.