Some hot air, some cold air

I have a 2002 Dodge Ram 1500 4.7L 4x4 Quad Cab pickup truck. The problem is that on the drivers side vents (both the face, and floor) the air comes out “luke warm” at best. On the passenger side of the truck, the air comes out piping hot. When it is turned to defrost, it all comes out hot on the dash. Any ideas as to where the problem could lie? Since I drive mostly alone in my truck (rarely have passengers) if it was on the passenger side I would ignore the issue, but it’s the drivers side and I’m tired of the hour drive everyday with only the defrost going to stay warm. Thanks for any ideas!

I have a similar vehicle, Sport model, with the same problem. Apparently, this is a fairly common problem. I’ve researched it and found, much to my dismay, and wallet, the following. Since I’m not a mechanic and got this second hand, it may not be etched in stone.
There is a device called a “blend door” which regulates how the heat is dispensed from the heater. It needs to be replaced to balance off the distribution of heat. It is located,I think, on the front of the heater. The entire dashboard must be taken off and the part installed. The operation requires at least 5 hours labor, plus the cost of the parts and the ability to install it. The article I read suggested the job be done by a Dodge dealer.
Good luck with your problem. I’ve decided to ride out the storm and turn the heater to high, the blower on high and the directional dial all the way to the left. Thus I get good heat throughout the truck, everywhere but on my feet and legs as I drive. I feel the cost would be sky high to have the blend door replaced.
Please, post a reply if you are successful or find another way to get heat on your feet.

Dominic (and jmc62446),
Sorry to pass this along but it very well COULD be your blend door. My '03 Ram QC 4x4 4.7L experienced the EXACT same problem. It was far too cold to deal with that cool breeze when it is 14 degrees outside. I took mine in and was given a broken blend door. so I drove my truck home and STILL froze. I took it back and they decided the heater core must me blocked partially. At any rate I did get a new blend door and a new heater core for just under $600. So if you DO take it somewhere make sure they check the heater core since they are already looking at it while they have the entire dash taken out of the cab.
Good Luck!
Matt