Heater Control

[grose67]

The position on my heater/AC control seems to be screwed up. I can set it for the AC to come out the dash vents and it works fine for a couple of minutes, but then the air flow seems to get directed elsewhere. I can turn the switch to defrost and after about a 5 second delay I can hear the door close in the duct work. When I switch it back to dash vent it works fine for another few minutes then goofs up again.