I am trying to figure out what is wrong with my folk 2004 heater controls this is on a gas engine if that makes a difference. When they try to switch it from defrost to the floor or to the head vents, I cant get any air to come out. I am try to find out what might be the problem. I know that on my 2nd gen that the vaccum pump help controls the ac/heater door. Any ideas?

Correct... It vacuum controlled so if the vacuum line is damaged the the vents will not operate properly.

Mode door is broke. Time for heater treeter.2003 Ram Cummins NV5600 with gauges and a Smarty! Not much more.Sent from my iPhone using Tapatalk

The blend door is controled by a electro-servo motor in the passenger's foot well. It's a PITA to get out but it can be done by pulling back the rug, carving a chunk out of the rubber insulation on the hump & using short right angle tools. Be very careful. The likely culpret is the flimsy plastic coupler between the servo & the shaft. They are expensive from Dodge, less so from HeaterTreater, or you can make your own, or you can repair the old one by glueing & then turning a reinforcing band & pressing it over the coupler in a vise (nice to own a lathe). You must reorient the gear drive & it will "relearn the new limits. (If it failed it went out of limit & shut down). MARK the motor as soon as you open the case as there is no mark to ID which way it goes. Wipe off the grease & find the raised mold mark on the bottom gear & set it to the edge of the top gear. Reassemble.

Correct... It vacuum controlled so if the vacuum line is damaged the the vents will not operate properly.

Mike do you know where the vacuum line goes into the cab on gas engine, I am lost on where to find it on a hemi engine?

The vacume line looks like a "wire". The Cruise Control uses vacume (located under the driver's side battery) so you might trace it from there. Depending on your year, you might have the vacume controled CAD (Center Axle Disconnect) with 1/2" lines from the front axle to the transfer case, back to the source. The "wire" sized line on Cummins powerd trucks, go into the wire bundle crossing over the engine & then entering on the passenger's side.