heater blows cool air
 

O.k. so I took the dive into a new heater core, as the heater was not getting hot. These are the things I did while on my adventure.
1. Before reinstalling the hoses, I blew thru them to make sure of no clogs...water flew out the other hose..no problem..no clog.
2. inspected mix door not cracked or broken...no problem
3.actuator opens and closes ok, I assume, I can hear the motor run and the door thump closed...no problem
4. water and anti freeze level good....no problem
Start vehicle,let warm up, turn on heat.....No Heat...hmmm
5. check hoses at core, one is hot ,the other is not....Problem...

any suggestions?

97 f150 4x4

I'll bet your heater control knob isn't actually turning the control shaft. Grab the temperature knob and pull it off. Check the inside of the knob - is the indexed part broken? Check the white plastic shaft the knob mounts on, is it stripped? on my truck, the problem was a stripped shaft. Using needle nose pliers, I was able to turn the shaft and -low and behold- heat. The next step was then to replace the heater panel assembly.

Keep us posted.

Weak water pump. Pull it and see how much of the impeller is left.

I have thought of that, but have not checked it yet. To the best of my knowledge, over 200,00 mi. and I have never replaced it

everything else seems to work ok theoretically, but that is something to try that I have never thought of

It only takes 30 seconds too. Just yank the knob off and have a peak. Here's hoping that is what it is. Simple and easy to fix.

A stripped knob won't cause the heater hoses to have different temps. Guess again.

I did not pull the water pump because it does not run hot the temps are good. With that said, it acts like maybe not enough circulation pressure to push thru the core being the hoses circulate from the back of the engine. hmmm....

Yeah. That's often caused by a worn out water pump.

Then next step is finish the dash and pull the pump...will advise of findings

:-banghead

UPDATE:

impeller on water pump non existent...no water circulation and never ran hot...WOW...replaced water pump and now there is heat

Good call SHO, I've heard of other vehicles prone to w/pump impeller wear but not these engines. Maybe just a mileage factor?

i have not heard of impeller failure either. Is this due to bad antifreeze or is there some other cause ?

Can you take a photo of the old one?

The Model T didn't have a water pump either. Woo Hoo! Now a Thermosiphon F-150!

Sure seems those heads would glow in no time, and trigger the alternating firing fail-safe scheme into shutdown.