I have a 2000 Monte SS. when I tried to use my air conditioner the other day , only got warm air. Got ouside car and checked under hood, compressor was not running although inside A/C lite was on. It was 91 degrees outside. Any suggestions as to what my problem could be?

Either your ambient air temperature sensor is bad, your refrigerant has leaked out, or there is another mechanical or electrical problem. Best thing to do would be to bring it to a shop and have them check to see how much (if any) refrigerant is in there.. this is the best place to start.