Dodge truck Heater problem

[7288cdn]

I have an 04 Dodge 1500 with a defrost problem.  The air coming out of heater on defrost is 120 degrees F.  If I direct the air to the floor or dash the temperature is 140.   My mechanic says this cannot happen and I agree but the thermometer does not lie.  It is not the famous broken door problem because the air goes to the various outlets as directed.  Dodge builds them so they have to use outside air for defrost but I have disabled that for the test.  Open to ideas.  Thanks.

[snoshoe]

Is the AC running in defrost to dehumidify?

[7288cdn]

The AC was running but only brought up the temperature a few degrees when I unplugged it.  The temperature difference is enough that it is unpleasant to hold the thermometer in the airstream from the dash but not so from the defrost outlet.  

 

[nomorejohndeere]

When you run it on "split" where it does defrost and some other vent system is it the same result?

 

[IHKeith]

It sounds like a HVAC door problem, if you are getting good heat on all other settings it almost has to be a door issue, the only other possibility I can think of is if by fluke of design there is more airflow over the heater core in defrost and the core is slightly restricted, and at idle it doesn't flow enough, this would be proved if the heat increases in defrost with higher engine RPM

[augercreek]

I have the same problem with my 03. I thought it could be a cabin air filter but, they don't have one. Where does it get it's air? Could it be plugged up with mouse nest? Where is the air inlet?

[augercreek]

THERE ARE SOME TUTORIALS ON YOUTUBE. I FOLLOWED ONE OF THEM AND FOUND THE AIR FLAPPER BROKEN OFF SO IT WAS LAYING OVER THE OPENING FOR THE FAN. BY DROPPING JUST THE FAN DOWN YOU CAN REMOVE THE FLAPPER THROUGH THE HOLE. IF A OLD 82 YEAR OLD LIKE ME CAN DO IT ANYONE CAN ! THERE CAN BE A COUPLE OF OTHER THINGS THAT CAN CAUSE LOOSE OF HEAT SO LOOK AT THE VIDEOS. iT TOOK ME ABOUT A HOUR TO DO IT AND NOW IT'LL ROAST YOU OUT, LOTS OF HEAT NOW. THIS SEEMS TO BE A COMMON PROBLEM WITH DODGES.

[sandhiller]

15 minutes ago, augercreek said:

THIS SEEMS TO BE A COMMON PROBLEM WITH DODGES.

And my old 99 Dodge has the bad habit of positioning spent .223 casings in just the right place to keep doors from functioning fully. ☹️😄

[cobfly]

7 minutes ago, sandhiller said:

And my old 99 Dodge has the bad habit of positioning spent .223 casings in just the right place to keep doors from functioning fully. ☹️😄

That's why I shoot a 22 mag.

[iowaboy1965]

120° isn't enough? I'm lucky to get anywhere near that on some of my old clunkers...😄😄😄😄

[from H to 80]

Dodge has a bad reputation for plugging heater cores, the crud settles on one side and depending on which direction the door is positioned determines where the air flows. The problem is it costs 1500$ to replace a 75$ heater core because the whole dash has too come out. I hope that is not your problem,but it sure sounds like it too me. We had to replace one in my wife's 2016 last year it would only blow lukewarm air as well.

[ky966boy]

22 hours ago, sandhiller said:

And my old 99 Dodge has the bad habit of positioning spent .223 casings in just the right place to keep doors from functioning fully. ☹️😄

.22 Casings in the blower makes a lot of racket happen to me several times guess I’ll never learn .

[oldscoutdiesel]

I replaced the heater core in my '96 Dodge dually a while back.  As said, you unbolt a lot of the dash and hang it from the ceiling to remove the core.  They also like to leak which allows opportunity to R&R the heater core.