I just purchased a 78 and the air blows on the floor no matter where the contol is. Does anyone know is this vacuum or mechanical control? I have not had time to dig in yet, but what should I look for? Thanks

 

Yes, the shop manual states that the blower starts as soon as the key is in the "on" position. I have the GM shop manual for the '81 Corvette. It covers only that one year and has afew things that Chilton and Hanes don't. I buy atleast the Chilton and Hanes manuals for every car I own as soon as I get the car. (the 'Vette's GM manual was a special situation for my special car. LOL) I find that no matter how much you know, the manual always comes in handy. But the manuals have mistakessometimes, BE CAREFUL!!! ie: 2 Chilton manuals I have say that the camshaft gear(sprocket) bolts should be torqued to 65 ft. lbs. WOW!!! That #8 bolt will snap before you ever get there. But it is rare for mistakes like that.) Good luck turning wrenches on your car.

 

The heater-A/C controls are a combination of cable and vacuum control, I can't remember which air diverters are controlled by vacuum but they can be accessed from under thedash.