I bought it 2 years ago and there was never much heat in the winter and I thought that it may need a new thermostat so I replaced it. That did not do the trick. Still blowing cold air. The hose from the intake is hot going to both cores but the hose returning from both are cold. Is there a heat control valve that I have not found? Could really use some help on this one. Thanks.

 

My '97 Expedition will burn your hands with hot air coming out if you let it. No heat? Maybe coolant flow through the cores [ I don't think so] I'm more inclined to think that no air is blowen through the core, but both cores? No way. I don't think the coolant bypasses the cores with a shut-off valve.

So when you shut off the engine, source of a necessary 'to operate' the servo's...vacuum, and when you cycle the heater *** do you hear the vacuum operated servo motors opening and closing the air vents between fresh air, outside air, floor vents, dash vents, and defroster? If not why not? An air bubble in the cooling system. Need to burp it?

What stops air and coolant from passing through both cores? Were gona need to look~see in the manual. Gotta be simple.

skip.

 

Thanks Skip I will keep looking and try to (burp) the system.

 

I have the same issue with my 4.6l. I replaced the t-stat still cold. The guys at Oreily's seem to think that i need to replace the heater control valve.

Any thoughts?