Defroster air?

[Luis_gz06]

When I turn my air on (a/c), and switch to defroster mode, it only works once and when I put it back to blow air through front vents, it won't work. I have to turn off the blower and turn it back on for it to switch back. Then I try again and put to defroster and nothing. Gotta turn off the fan and back on every time to make the selections work. What could it be? Thanks!

[davepl]

This diagram might help you debug it. The temperature door controls where the air gets heated/cooled. So that's where to look for the "wrong temperature" of air. The outlets door controls where it goes, defroster or heater vents. The last door splits it up (defrost) or down (floor). The vacuum cans for fresh air and stuff won't come into play for what you're describing, so it seems to be a cable/door issue to me.

[Luis_gz06]

Cables are fine. So could be my ac diverter box?

[davepl]

Dunno. Almost sounds like the air pressure is holding a door in place and not allowing the cable to overcome it, but that'd be weird.

Work your way through the diagram sitting in the truck and see if each cable&door does what the diagram predicts it would, and let us know where it diverges.