Heater

[bucks77ford]

I"m finally having to run my heater in my 75 Supercab and I had replaced the heater core when I was changing out my blower motor back in summer, but the heater just doesn't feel very warm. I had also replaced the heater control valve. I do have a vacuum issue somewhere since when there is a load on the motor (pulling uphill) I loose the air from the front panel vents and it switches to defrost vents. My thought is that the heater door isn't opening up all the way, but what else might cause the heater not to feel very warm.

 

[fatherdoug]

When you say you replaced the heater control valve, are you talking about the valve on the inlet side of the heater core that is in the engine bay? Doesn't that also open/close on vacuum? If you have vacuum issues with the blend door, then you might also have issues with the valve in the engine bay.
Just a thought.

 

[bucks77ford]

When you say you replaced the heater control valve, are you talking about the valve on the inlet side of the heater core that is in the engine bay? Doesn't that also open/close on vacuum? If you have vacuum issues with the blend door, then you might also have issues with the valve in the engine bay.
Just a thought.

Ya, the valve in the engine bay. I am also thinking its a vac issue. I am gonna manually keep the valve open and see if that helps. If it does than I know its a vac issue.

 

[DNFXDLI]

Might be the vacuum actuator that operates the blend door, the vacuum control on the heater control or a loose or cracked line.

 

[Mil1ion]

If the water valve is okay..then..Blend door motor issue or No T-Stat

 

[donaldderby]

I know you posted a while ago but in case the issue isnt resolved i had the same problem. The cause...No insulation around the heater core so cold air was just blowing past it. The solution was to reremove the heater core pull the little insulation that was left the cut up some 5/8 pipe insulation 250 deg rated and hi temp silicone it to the side. Its a tight fit getting it back in and putting the cover on but now i have hot heat in minutes where as before i couldnt get above warm in a few hours. FWIW its 28 degrees here now so yes the heat is hot