clicking noise on 2005 Chevrolet Silverado 3500

there is an load clicking noise coming from the dash in the area if the air conditioner controls. It does not happen all the time but most. Sometimes if you move the temp controls all the way down it stops sometimes not. It has done this since new and no one has been able to pinpoint the problem. Anybody have any ideas?

1 answer
This sounds like a stripped temperature door actuator. They are plastic and when the wear out the teeth just grind and click away.