Not for my Trans Am, but it's a Sunfire, so it's at least a retarded bastard cousin...

Driving home from work the other day, a/c was blowing fine, and out of nowhere just started blowing warm air. The compressor's pretty much impossible to see, so I can't tell if the clutch is kicking in, but when driving the car and turning the a/c on, it feels like the compressor's kicking in (slight lug on the engine). I figured I'd just get one of the refill kits at Advance Auto since getting the daily into a dealership isn't going to happen for a few weeks and it's been 35C here for a while. Hooked the gauge up to the low side (right by the evaporator) and the needle instantly went to 150psi. Now, I know it shouldn't be nearly that high with the car and a/c system running, so I'm trying to figure wtf is going on. The valve had a blue cap and the gauge would pop on to it; the only other fitting was red (blue and red, at least on the compressors at work, are low and high) and the gauge wouldn't fit on it, so I'm relatively sure I was on the low side. A/c has always blown really cold until it just completely stopped working the other day.

Going to throw a good set of gauges on it at work tomorrow morning just to make sure the gauge on the little refill canister isn't just fubar, but off the top of my head, I can't think of any reason why the low side would be that high. I initially thought I might have blown a seal somewhere and vented all the refrigerant, but I can't see how that'd explain 150psi on the low side.

 

well, you may have overcharged the system without actually weighing the refrigerant that was already in there... Low side pressures should range 25-45. A restriction in the AC system will make pressures increase, maybe a clogged orfice tube. Make sure the damn compressor is kicking on first!

 

I didn't put any new refrigerant in - as soon as I hooked the bottle up and saw the gauge showing 150psi, I unhooked it and went, "Well, ****."

Going to try an inspection mirror tomorrow and see if I can confirm if the compressor is actually spinning up or not. If it's not, what could be causing the problem?

 

If the compressor is not kicking on, unhook the low side pressure switch, then take a paperclip or cotter pin and loop the circuit on the pigtail you unplugged, by sticking it in the connecter on the pins. The compressor should turn on regarless of the pressure in the system. If there is pressure in the system you may then have a bad pressure switch. if it still doesnt turn on, you may have a bad compressor.

 

Similar problem with mine a few days ago. Pre-freon add, low side registered over 70. (more than double what it should be) High side measured 200. System had never been touched prior. No recharges, etc.

Gauge reading seemed high but we tried adding a little freon - no dice. Thermometer at vent confirmed that air coming out was same temp as air outside of car.

AC shop pulled out all of my freon out - and then put it back to factory spec. Long story short, compressor is unable to pull pressure down to where it should be - and was diagnosed bad. If you want to see all the details and a link to a diagnosis chart I found helpful - look at my other post about an AC not cooling and low pressure reading that's too high.

Hope that's not what is wrong with yours - but maybe there are some details in there that will help you rule something out or make an identification.
Good Luck!

 

Is your auxillary air fan coming on? Did you get a good set of gauges and take a look at both the high and low side yet?

 

Tried my gauges at work but they won't fit automotive a/c fittings - they're designed for normal industrial fittings. Didn't realise that till I tried to hook everything up.

Can't really tell if the fan is coming on or not...can't see the a/c compressor enough without the car on stands to tell if it's cycling or not, either. Probably just going to wait until the spring and have a shop look at it, since it's starting to cool off here now and work is too busy for me to take a day off and babysit the car at a shop.

 

Should be able to hear the comp kick on & off at an idle. It's a click & whir sound. I also think if it is running you have a clogged orfice tube. Evac it & open the union where the indent is and pull the orfice tube out w/a needled nose pliers and I bet it is a solid black mess. Good luck!

 

I'd pull it down if I could, but I don't have access to a vacuum pump. :\