i've had this car for 9 years. when i first bought it, the AC worked for about 2 weeks, then crapped out on me. i was too broke to do anything about it, so i just dealt with not having AC. the winters weren't cold enough to fuss much with the heat. now, the blowers work just fine but there is absolutely no cool air coming from the vents. when we charged the coolant, nothing happened. also, the heat doesn't work if the temperature is below freezing. that could be attributed to the racing thermostat we had to install about 7 years ago to stop an overheating problem that i'd been having. i'm kind of at a loss as to what might be the issue with the AC, though.
blower works, but there's no heat/cooling. on 1999 Pontiac Sunfire
The lack of cool air sounds like an A/C issue. Have you checked to see if the A/C compressor is engaging? It is possible there could be a leak and low freon level is not allowing the compressor to turn on. I would get it checked for a leak in the A/C or a possible compressor issue. This usually requires an A/C machine and gages to properly check and diagnose the system. As for the heating issue, if the proper thermostat is not installed that can cause an issue if the coolant isn't allowed to reach a normal temperature.