hey guys, i've recently just purchased a 2004 holden zc vectra, the thing is when i unlock the car first thing in the morning i hear this strange tat-tat-tat noise coming from behind the glove box...and when i have the air con in economy mode the noise is not there but when i switch the air con on and then off the noise comes back for around ten seconds everytime i turn the air con off and back to economy mode...now i have a theory and was wondering if someone could point me in the right direction...im guessing it has something to do with the dualzone climate control and that the air conditioner stepper motor is stuffed...like the internal gears are stripped when i have it in recirculation mode...any other guesses

cheers guys