poor heat from both heaters

2001 FORD EXPEDITION
168,000 MILES • V8 • 2WD • AUTOMATIC
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ANDY 47
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2001 Expedition 4.6L. Heat was extremely hot but suddenly it stopped. Both front & rear blow luke warm. Replaced thermostat twice, replaced radiator, replaced water pump. Blend doors work because it changes from cold to warm. Hoses at the fire wall are all hot. No leaks or odors inside. What is common to both heaters to cause this problem?
Thanks.
Jan 18, 2011 at 2:32 AM
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JACOBANDNICKOLAS
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If both heater core hoses are hot, the blend air door sounds like the problem. If it isn't fully opening, you are going to get a mixture of hot and cold air. Thus, your heat is warm and no longer hot. Check to make sure the door is fully operational.
Jan 18, 2011 at 8:49 PM
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ANDY 47
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If it is the blend door, why do I not get heat out of the front & rear? The temp turns cold when turned to cold & only gets slightly warmer when going to hot. As the rpms go up, the heat increases some what.
Jan 18, 2011 at 9:29 PM
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JACOBANDNICKOLAS
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That is a good question. However, if both heater core hoses are hot, then the coolant is flowing through the heater core and should produce heat unless there is something stopping it from coming into the vehicle. The only thing left is the blend door. As far as the RPM's, you are forcing coolant through the system faster (hotter). If you didn't tell me both heater core hoses were hot, I would question an air block, but that wouldn't make sense now.
Jan 18, 2011 at 9:33 PM
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ANDY 47
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Is there an easy check for the blend door? Should I do a complete flush with a kit first?
Jan 18, 2011 at 10:33 PM
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JACOBANDNICKOLAS
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I would say no to the flush. Based on your description, it sounds like the coolant flow is perfect. As far as the blend door, there really isn't an easy way other than taking things apart to access it.
Jan 18, 2011 at 10:49 PM
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ANDY 47
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Can the blend door be replaced without removing the dash?
Jan 19, 2011 at 12:31 PM
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JACOBANDNICKOLAS
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Part of the dash needs removed to access it.
Jan 20, 2011 at 4:24 PM
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