I've got a 1997 Ford F150 with light air flow through the floor vent anytime the blower is on. Regardless of the mode selected, I get a light breeze through the floor vent; which isn't a problem until I want to get air to the floor. From what I've been able to gather, my problem is either the mode switch or one of the two mode doors that divert the air flow. Is it a crap shoot as to where I start to try and solve this problem? Here are a few of the details, if I select ...

Panel, -------> I get heavy air flow through panel vent, a little through the floor, and nothing through the others.
Panel/Floor, --> I get heavy air flow through panel vent, a little through the floor, and nothing through the others.
Floor, --------> I get heavy air flow through Defrost vents, a little through the floor, and nothing through the others.
Defrost/Floor,-> I get heavy air flow through Defrost vents, a little through the floor, and nothing through the others.
Defrost, ------> I get heavy air flow through Defrost vents, a little through the floor, and nothing through the others.

 

I read a post that said the mode door that directs air between the floor and defrost was electric, is that true? I don't see any electric actuators.

 

I was able to fix my problem. The cylindrical shaped, vacuum controlled, actuator just to the top-right of the gas pedal came disconnected from the door that it controls. The actuator has a 2” – 3” metal rod coming out of the top of the actuator with a 90 degree bend at the end. The metal rod resembles an L shaped 5/32 allen wrench, which is what I used to reach up and hook the mode door so I could pull it down and hold it with my fingers. After removing the two screws that holds the actuator in place, the actuator dropped to the floor. If it would have been connected to the door, it would have dangled there without screws installed. If your vacuum lines and rotary switch appear to be okay, and you have symptoms similar to what I described above, you may want to verify that your actuator is connected to the mode door.

FYI, if you are having a problem with the distribution of air between the vents, you can visually verify at least one of the two actuators is working properly. After locating the cylindrical shaped one by the gas pedal, look a little further up behind the dash. The second actuator is a few inches up and to the right of the first one. As you select a vent, you can see this actuator function.

 

Excellent posts, thanks for the info! Glad you were able to get it fixed.