heater not working 2004 expedition

[PATRICK GARRISON]

hello all my heater just stopped putting out heat the blower works great a/c works sounds like all controls are working looks like the heater control is working the heater in the back also does not blow hot air please help

 

[Hamfisted]

Are you the original owner ? Are your heater hoses hot to the touch ? Is the hot water valve opening ? Have someone cycle the heat temperature selection on the dash controls and watch to see if the hot water valve control arm is moving. Or pull the vacuum hose off of the valve and see if it moves to the open position. But first, feel the hoses to make sure they are in fact getting hot water through them.
If you're not the original owner, a previous owner may have unplugged the rear temperature control blend door actuator to keep it from "clicking" after it's gears broke. You can lift up that rear tray in the rear quarter panel to inspect it and see if it is unplugged. Or the actuator may have broken a long time ago and quit clicking already. But the rear heater core gets hot water continuously, there is no control valve for the rear. Just the temperature blend door in the rear box.




Rear blend door actuators. Green circled is high/low vent outlets. Red is temperature actuator.








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[JerrySmith]

Sounds like what is happening with mine, it just started the thumping noise this summer.

 

[RoadRunner42]

Did you resolve this? Was it the valve, the core or the blend door? I'm having similar issues. Really no heat at all. Just replaced Thermostat and some hoses because it all kind of exploded. But I had heat last year. I have zero now. Assuming it's not the core, could it be the valve? I don't know.

 

[whtbronco]

Sure it absolutely could be the heater valve and it's easy to check. It could be 1 of multiple issues. Do you have air flow from the vents and the air is just not warmed?

Checking the heater valve. Without vacuum the valve is designed to default to the open position allowing warm/hot coolant to flow into the heater core. So note the arm orientation on the heater valve with the engine off. Start the vehicle and see if the arm moved 90 degrees this will at least verify that you have vacuum to the heater valve. It should also indicate that the valve has closed. Wait until the vehicle is near operating temperature and ensure the hose on the engine side of the valve is warm, the heater core side should be quite a bit cooler. Now select heat and see if the moved back to the default orientation again and check the hose on the heater core side of the valve again to ensure it warms up.

It could also be the heater core is plugged up. If the hoses disintegrated inside bits of the hose can plug up the heater core and radiator. The coolant can also get gummed up, if not changed regularly, and plug the heater core.