The HVAC vent control is erratic on my truck (see sig). I can switch from floor to dash to defrost vents and sometimes the vents will change (after a while), but mostly does not. It seems like what ever kind of motor is used for controlling the vent doors is sticking. Anyone have any experience with this? I have an extended warranty, with a $100 dedectable, which should cover the repair, but would perfer to fix it myself if there is a simple fix. This might very well be the first real problem I've had with the truck in 4 years.