rick555

I've been troubleshooting this problem for quite some time now and i could use some advice. I have not had heat in the front but the heat in the back works great. This seems to be a common problem with this model and I have gone through everything i can think of. I have removed my glove box, cut a small hole into the heater box and watched the blend door open and close and it works properly. I have checked the heater hoses at the firewall and the inlet is hot going in and cool coming out. I suspect that I have a plugged heater core. I can't find any evidence of the core leaking. I have attempted to flush the core twice now using a garden hose, and i am getting some flow even better when i back flush the core. When i think the core is flushed i start the vehicle and I get heat up front for a little bit and then it goes cold again. Does the 99 have a heater control valve? If it does I can't find it anywhere. I keep hearing the 98 expedition has a heater contol valve but I don't know about the 99. I'm not looking forward to changing the heater core. Thanks

Bert

I'm pretty sure that there is a control valve in line. Check the inlet hoses and you should see it in the hose.

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Bert

rick555

On my vehicle, the heater hoses have a tee on each hose so that coolant can also be directed to the back heater core. The hoses that go to the back dive down towards the wheel well on the passenger side and they connect to steel lines. I have not traced the lines from this point but there is no valve that i can see above this point. thanks again

Bert

Check this out. A/C Works But No Heat in my 2003 Ford Expedition

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Bert

rick555

Thanks Bert. I'll check it out.