2002 Sport Trac Heater Core issue

I have a 2002 Explorer Sport Trac that the heat just quit. It went after I turned the control knob to cold, and it stayed there overnight. The next morning, I had no heat and the Ford dealership says that it needs a heater core, and to fork over $900.00. The knob itself feels like there is little to nothing "behind" it, if you know what I mean, no resistance.

2 questions. 1. How do I narrow that down, if their diagnostic says heater core, to the knob?

2. Is there a better way than shelling out $900.00 for a heater core replacement? Can I do it, or a regular garage do it? Can it be flushed?

Thanks in advance.

Welcome to the forum!

Did you actually take the Sport Trac to the dealer for a diagnosis, or did you call them over the phone and describe the problem?

Does the blower work fine, it just blows cold air? Does your heat guage in the instrument cluster indicate the engine is getting up to temperature?

Have you checked the inlet and outlet hoses of the heater core to see if they are getting hot? If the inlet is not getting hot, the heater control valve may not be opening and letting coolant flow to the heater core. This could be due to the valve being bad or there being no vacuum to the valve. You also should verify the coolant level is correct.

The factory service manual indicates that the temperature blend door is electronic and the temperature selector is a potentiometer. I wouldn't necessarily expect a potentiometer to have much resistance to it when rotating the knob. To check the blend door actuator for proper operation, you'll need to be able to get to the blend door and have a multimeter as well as understand some basic electronics. I think the actuator is located behind the glove box.

If the problem turns out to in deed be the heater core, then depending on your comfort level working on vehicles and pulling the dash, you may be able to do the job yourself.

-Rod

Thanks for responding.

1. I just got this vehicle back from an accident to the front (about $6000 worth). The dealership says it has nothing to do with it.

2. They did supposedly "diagnose it".

3. It blows cold air.

4. Coolant is full.

5. Engine gets to proper temperature.

6. One of the intake hoses gets warm, the other stays cold.

7. I noticed there is no vacuum (pressure) coming from one of the vacuum hoses that comes from the heater.

Thanks again for the response. Which valve is it you speak of that could be stuck? I'll pull some info from the manual on the electronic door and see if I can get at it.

Any futher thoughts?

The heater control valve will be inline with the heater core inlet hose under the hood. If you are not getting vacuum to or from the heater control switch, you need to remedy that before condemning the heater core. Vacuum controls the heater control valve on yoru Explorer.

-Rod

The heater control valve will be inline with the heater core inlet hose under the hood. If you are not getting vacuum to or from the heater control switch, you need to remedy that before condemning the heater core. Vacuum controls the heater control valve on yoru Explorer.

-Rod

Ok, thank you. I will try that first and go from there.