2003 Dodge 3500, Cummings. Heater blows out defroster when floor setting is selected. With Floor/Dash Vent selection, some blows out dash, the rest out the defroster, very little out the floor. All other selections work fine. Dealer wanted $800+ to look at it under 75K extended warenty with 60K on truck. Said only the vent motors are covered, not labor to find or correct. ?? It is a real project to remove dash to get to motors and posibility exists that the dash (electric) selector switch could be at fault. This does not appear to be a vacume operated system. Ideas???? Through this forum, found one referance to TSB 24-004-03 http://www.dodgeram.info/tsb/2003/24-004-03.htm that may be germane to the problem.

 

That sounds exactly like what I had done. They have to remove entire dash board to get at door "flap" 1800 for me by the time it was all said and done. Sorry to hear about yours...
tom

 

Before ya take it in for major surgery, check the actuator on the drivers side of the heater duct (under dash near floor), to make sure that the vacuum line to the actuator is not loose, kinked or disconnected.

Hope this helps a little.

Gary

 

Not sure on your truck, but I have an old Ford and when the resistor in the heater controls gets burnt the default is to push all the air to the defrost postition. My Dakota is the same. Part is like $12 at dealer. But maybe life can't be that simple.

 

A vacuum leak anywhere on the truck, under the hood or to the 4wd, will cause the heater to default to defrost.
It doesn't take much, just a cracked hose will cause problems.

 

The part that scares me is he say's ~some~ comes out the vents and the rest out the defrost. I hope his is easy but it sounds like the stupid plastic key/spline on the door coupler striped out.
Keep us informed.

 

'03 has no vac lines.

'03 is all computer controlled.

Yeah, sounds like the door is sticking or busted. Maybe an AC shop will give you a better labor rate but they will need the DC scanner tool to reprogram the door stops. Looking at the manual, it seems to be a "Pull the dash" "Pull the AC unit out and work on it on the bench" type of repair. I wish I had better news for you. While they are in there, have them check the other doors.

 

On my '97 CTD , the defrost/floor vent door is controlled by a vacuum operated relay/actuator located just to the right (toward center ) of the accelerator pedal . In other words you can get at it without tearing out the dash . In my case a check valve in the vacuum line had stuck open with the result of the vacuum actuator filling with engine oil . The actuator was about $40 at my friendly Dodge dealer . A simple cleaning of the check valve seemed to cure the oil filling problem , now going on 2 years . Small hands with long fingers are needed to remove/install the actuator but it didnt taks but an hour for my short /fat hands .