I have a 2006 Grand Prix base and it won't switch off defrost. I know defrost is the default when something breaks and something must have broke. This does not have the automatic climate control and does not have dual climate control. I dug down to the actuator, which seems to work fine, then turned whatever the actuator turns with a screw driver and nothing changed, just stayed on defrost. Is there a common problem on these cars, what part am I looking at that isn't working, I think I might be able to find out more information if I just knew the terminology.