I have a 2002 Dakota. The heater will blow out cool air when on a high setting, blow out warm air on a low setting. i have reversed flushed the core, no help from that. Can anyone give me some suggestions. i am freezing. Just started doing this all at once

 

what does your engine temp get up to? your thermostat may be stuck open.

 

The radiators are also known to plug and reduce the coolant flow.

 

The engine temperature stays about middle of the gauge. it has always been there after running. it doesn't run hot nor does it run cold. The heat used to run me out of there and now all of a sudden i can't get any heat except when i have the fan turned to low, i reversed flushed but didn't help. i thought about changing thermostat but the truck is not over heating and it isn't under heating.

 

strange. there is obviously a problem with the heat exchange in the heater core if your engine temperature is normal. is there a possibility that it is clogged with dirt/dust not allowing air to properly pass over the coils in the core?

 

sounds like a blend door issue to me

 

^^ smart man. i'll bet youre 100% right about that

 

this wouldn't cause blow back from the overflow. if it is the blend door then it would just mess with the air flow. The problem that i have is that i get very little heat, and this is on a low setting, anything higher and i get cold air. Also the same time that this started happening i started leaking antifreeze through the radiator overflow. i wonder if the thermostat is stuck have way? Would this cause this heat issue and leaking issue

 

if that were the case then your engine temp would not get up to operating temp

if your blend door does not open much, you will get a little heat flowing from the core, then, as you increase the fan speed, the air has to come from somewhere, easiest place is from the cold side.
the antifreeze overflowing might be caused by having too much coolant in the radiator, it does expand as it gets hot

 

how hard is it to take the dash out and work on the blend door?