Originally Posted by Spartan7
I'm not sure how Vettes are set up, but on F-bodies the mixture door is controlled by a cable. If yours is the same way, pop the cable off the back of the HVAC controls, then stick a screwdriver in the slot and spin it to close the mixture door. If it's electric, there is a motor on the mixture door shaft. You can pop the motor off and spin the shaft by hand.
Cool, I'm thinking its a motor on the Vette's than.....because they spin so easy with no resistance like our F-Bodys.
I'll try to remove the panel and check behind it.......