NO HEAT I turn my heat on and it only comes on sometimes. The fan control switch does nothing. And it randomly comes on and works fine.

damaged fuse in the fuse box.

refill the ac

I would check for a bad connection on the blower motor resistor.Its located on the passenger side mounted on the heat duct with 2 screws.Turn the ignition and fan switches on then wiggle and pull on the connector usally if the resistor has a poor connection it will comw on.These resistors get hot and sometimes they melt the connector causes it to loose its connection.

read the owner manual to see how the auto works. try the defrost mode whcih is a fail safe mode and should always come on unless a major system issue.

Sounds like the switch,I have had the same happen. Won't work on 1or2 but 3-4 worked fine. The next day 1-2 worked....? With out a meter to check it will be guess work.

i have seen this before its the igntion switch . on the lock and key but the switch its self wich is located under the plastic cover on the steering colume

The pontiacs have an issue with the ignition switch, I have a 2001 grand prix that did the same. The ac fan would only work on 5 and the headlights would go off if on 1-4 replace the switch and all is fine.

Hi,
can you listen the ventilation fan working?
check fuse/ventilation fan engine