The a/c on my Grand Prix isn't working...?

I have a 2000 Pontiac Grand Prix. When I try to turn on my a/c it will only come on sometimes. It comes on more often on the blower setting 5 than any other. If it's night time and the a/c is set to on but not functioning, my lights (which are automatic) won't come on until I turn the a/c off. Also, the rear window defroster button on the same panel as the a/c won't work if the a/c is switched on but not functioning. A mechanic already replaced my blower motor and resistor and it didn't fix anything. He wants to replace my ignition switch now, but it just doesn't make sense to me that it works sometimes and other times it doesn't. Any suggestions?

The a/c on my Grand Prix isn't working...?
sounds like a wiring harness has gone bad to me, either that, or you have a ground problem. You will need to pull the A/C control panel and start looking for wiring problems, melted. or pinched. Good Luck
Reply:Your problem is your ignition switch! That was very common in those cars as your controls for the A/C heater and such was ran thru that switch. They always went bad. Your mechanic is right on that but I would challenge them on the cost since they did not fix this the first time as a simple voltage test and proper diagnostics would have told them the ignition switch is bad.





Hope this helps!


Owner of 97 Grandprix