I have a 2005 Chevy Cobalt; its heater works fine, but AC doesn't seem to work at all. Fan works, but even at cooling set to max it just blows room temperature air. What could be the reason?
The most likely causes are a freon leak or a broken drive belt. Frequently the leak is from an "O" ring on the back of the compressor. You can buy recharge kits at auto supply stores that are designed for the DIYers. My experience has been that if you are not familiar with the system it might not be cost effective. It will usually take two and sometimes three kits to find the leak. If you shop around you can find a shop that might be able to fix it for the same cost.