Just the other day when I turned on the defroster on hot I noticed that the air coming out of the defroster was cool. Truck was at temperature. So I switched back to the dash vents and the air came out of them hot. I switched back to cold and the dash air blowed cold. Switched it back to hot and it blew hot. So then I switched to the defroster and the air was cool. I can't get hot air to blow out of the defroster but I can out of the dash vents. Cold A/C works good out of all the vents when selected. Door I have a broken door or another problem? Thanks.

 

No one has had this problem before? Wow. Thanks anyway........

 

I wouldn't think that would be a blend door issue, or temp control wouldn't work in any mode.

These trucks activate the AC compressor in defrost mode (as a dehumidifier) so the air on defrost also tends to not be as warm.

I wonder if that could be what you are seeing.

 

I have the same problem with my 06 mega cab, I have replaced mode 1 & 2 doors, blend door and recirc door with heatertreater doors and new actuators, new t-stat one from cummins, not fixed yet, mine seems to blow warm air on recirc and cool air thru def vents when on defrost, my A/C doesn't work. I also noticed even on defrost with cool air coming form def vents I still have hot air coming from my rear seat vent. Am going to tear into my heater box again try new heater core since I need to replace the evaporator core anyway. The heater cores are very small.

 

This!

http://www.heatertreater.net/magento...ram-02-08.html