I have a 1996 Lumina with a 3.1 V6. When I'm driving at hwy. speeds, the AC blows fairly cold. (Not freezing, but comfortable) When car is sitting still while idleing, AC doesn't blow very cold. (Almost a warm feeling) Does anyone out there have any idea what could be causing this? Any help would be greatfully appreciated.

Welcome to AF, make sure the fans work with the ac, also the condenser is not blocked up with debris or bugs.

Has it worked well in the past, and just started to do this? Then it could be a little low on Freon. You will have to put a gauge on it it be sure. Be sure to check both the high and low side.

I have the same '96. I just replaced the pump, and with it the orifice tube and accumulator. I noticed that it does not get as cold as it used to. I also noticed that the orifice tube looked a little different, and I think that it is my source of the issue.

Thanks for your help guys. Will check your recomendations out and see if that helps.

I have the same problem with my 98 lumina 3.1
and have been dealing with it for 2 summers now , its great a/c as long as your movin 30mph plus conatant , but in stop and go traffic, nada worthless a/c , if its above 90 outside, and your not movin..........
i have never been able to find a cure for this problem EVER, ive posted here, at other wbody sites and nothing has ever worked, my system is charged properly, the fans work correctly, the only thing i can think of trying is to add another electric fan, i havent tryed this yet but iam thinking about it....
god how i miss r 12 cars, plus ive tryed keeping the reves up on the engine while not moving, and the compressor shuts off and the temp jumps to 70. if this was my old 78 caprice the air would keep cold, but in the lumina hell no......

If your compressor shuts off- that is a sure sign of an inop cooling fan (radiator fan)-- those V-5 compressors are designed to run continuously- UNLESS there is high pressure- check your cooling fan(s) are theyh on when a/c is on and idling?? Going down the road you have air across the condenser- at idle there is NONE unless the fans are running

Fan on drivers side runs when A/C is on. Fan shuts off about 1 minute after I turn A/C off. Passenger side fan does not run when A/C is on. Should passenger side fan be running when A/C is on and could this be my problem. I was told that it could have something to do with some kind of valves in the compressor. Is this a possibility?

Would need to have both high side and low side pressures- number one a/c failure mode is loss of refrigerant due to a leak- only way to know if charge level is correct is to take it out and weigh it-- or charge it to factory specs..so I highly suspect you are low on refrigerant.