I searched the forum and I couldn't find anything directly related to what I'm experiencing. I just drove back from Champlain NY to CT over the weekend after some bitterly cold ice fishing. On the way up and back, I found that I could make changes to the fan blower positioning (Defrost/floor, just floor, just dash, dash/floor) and everything was A-OK. This morning I attempted to switch from defrost/floor to dash/floor to warm up the hands and I got no switch over. Tried all the positions, stuck on defrost/floor.

Temperature control works fine and fan speed works fine as well. I'm not getting switch over between the different airflow locations. Any info is appreciated.

 

Actuator for the shutter door most likely failed. It's driven by vacuum so it could also just be a leak in the tubing running to it. Not sure where its located on your vehicle but most likely under the passenger side of the dash.

 

Check under the hood on the driver side near the firewall and fender. It should be pretty close to the top. That's where mine failed at. It all I did to fix it was cut off any part that was torn and push it back on the plastic T it came off of.

 

Thanks guys, I'll have a look later. Its freezing right now ha ha

 

The heat/defrost door actuator is the lower of the two actuators in this image.
It is located above, and to the right, of the gas pedal, just above the transmission tunnel, under the instrument panel.





As you change mode positions, the actuator needs to move the linkage on the top of the actuator, and the white plastic linkage that is attached to the blend door. Make sure the ports on the actuator both hold vacuum. The door should remain in the same position for MAX AC, norm AC, vent, & Bi Level.

 

if what captain said doesnt help, mine got stuck on defrost because of the T check valve on top of the brake booster vacuum line was rotted and leaking. its fairly simple to see if it needs replacing visually if not, just rub your fingers on it, if it crumbles or leaves a black residue on your hands, time to replace it.