heat only blowing hot on psgr side vents

alright guys this is driving me nuts. my tow pig/daily driver is a 2002 dodge ram 1500 quad cab 4x4. the problem i am having is this: when using my heater, it only blows hot on the vents that are to the right of the radio. the drivers side vents still work, and blow air just as hard as the others, only it is lukewarm no matter how long you let it run or how warm the truck is running. i checked the blower motor-works great on all speeds. both heater hoses get good and hot. all modes on the selector knob work and switch fine between them. has anyone ran into this problem and possibly know a fix? virginia gets pretty cold in the winter and im going insane trying to diagnose this.also, this is something that has developed recently, since the heat worked fine when i bought the truck in march. thanks in advance guys and any ideas will not go overlooked.

has nobody ran into this? BUMP

i see it happen all the time to GMC's, and its almost always an actuator up inside the dash. they will not open the heater door up all the way to those vents, but im not sure it its the same on dodge.

you either have a broken blend door, or sometimes the heat from the heater gets hot enough to soften the plastic on a blend door. when the door gets hot and you adj.something ie. floor, vent, def. the door will warp/bend. causing it not to seal.you will mostlikely haveto pull the dash and remove the heater box and find your prob.

To get to the heater you will have to completly remove the dash and drop the steering colum just to get to the heater if you want to remove it to work on it you will have to diconect the heater core and the A/C if you have it. The same thing you have to do to replace the heater core.