the fan speed selector works. My cold/hot lever works. But my vent selctor and a/c does not work. Do I need to buy a whole new part or is the a chip located somewere likt the toyota have?

I have another problem too. My cooling fan will not kick on. I have tested the fan itself and it works. Is it conected to the same sensor temp sensor as my temp guage? I pulled the relay from my other cavalier and tried that, and no change.

Yes I like cavaliers. I have a 88 and a 92, I did have a 90. I gave the 90 to my sister who thrashed it. I prefere the cav over hondas do to its fuel economy is better and less cav are stolen than hondas.

check the vaccum line behind your HVAC head, and see if that came undone.

They didnt work on my 89 when i got it either, found on the back side of the dash control, where the hoses gather into a round rubber piece, it had came loose due to one of those barbed washers that are perssed on coming loose and allowing a vac leak, pressed washer back on, put some epoxy behind the washer and no more problem