I was hoping someone might be able to shed some light on a heater problem that recently developed on my '02 7.3L F-250 crew cab. I have the stock two-dial heater/air conditioning controls on my truck with the temp controller on the left and the function selector on the right.

For those who might not be familiar, the function selector **** is in the off position when pointing straight up. There are three functions available when you turn to the left - 1) heater/fan blowing at chest level, 2) air conditioning, and 3) max (cab recirc) air conditioning. Turning this **** to the right accesses four additional heating and windshield defrosting functions.

The issue is this - the three settings to the left all seem to work as advertised. The a/c functions properly and the chest level heater/fan blows well and heats up nicely when adjustments are made via the adjacent temperature dial. When I try to use the heating/defrosting functions on the right side of the dial, however, I don't get any heat at all in any of the positions. The air seems to be coming out of the proper vents relative to the dial position. For example, when I turn the dial all the way down to windshield defrost, the air is definitely blowing out of the dash vents. Only problem is that the air remains at the ambient temperature even when the temperature dial is turned to full hot. Any ideas?

 

Wow, 75 thread views and no guesses?

I'll give it one bump before searching elsewhere.

 

It sounds like the blower door is not working in those positions.

I found your post because I'm searching for a heater fix myself. Mine's an early '99 and is getting no heat at all, anywhere. But I can see the door solenoid actuate the blower door as I flip through the positions, so that's not my issue.

I would guess your door is getting stuck, and not directing the air over the heater core. Or the door is not getting the message at all. Not sure if the newer ones are vacuum-actuated or electric though.You might scout around under the dash and see what's connected to the selector switch, then trace the wires/tubes for any breaks. A passenger could have kicked a tube loose, for example. It's possible the switch itself went bad, not likely but possible.

Best of luck, let us know what you find!
c.

 

Thanks, cc. Will do.

 

behind the glove box is the lever that controls the floor/def. open the glove box door squeeze the stop tabs in and lower the door youll see it .there is a guard it is in . lift the lever and you get heat .you can jam somthing under it for temp fix. I believe the control is behind the heater control head