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Old Dec 30, 2015 | 12:29 AM
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Heater problems

Ok i have a 1999 expedition 4x4 eddie bauer with a 5.4 liter engine with about 150000 miles on her. I am having trouble with the heat. Let me start off by saying i dont have dials on my panel its electronic so i push buttons instead of turning ***** for temp control. I am having trouble getting the heat to work. I have felt both heater core hoses and they are both hot and im not losing antifreeze so im thinking its not the heater core unless its just leaking a tiny amount. I get warm air when i put it on the vent option but its not as warm as it should be. I get warm air in the front and back when its on vent but again not like it should be. When ever i select any other option it blows at room temp. The a/c works great front and rear. So im left stumped. Could this be a blend door option if so i might as well replace the heater core while im in there and the dash is apart. Could this be the door actuator? Any help would be great. Thanks Chris
 
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Old Dec 30, 2015 | 10:25 AM
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If both the front and rear heat are cool, then it could be a stuck t-stat keeping the engine from reaching full temperature.
 
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Old Dec 30, 2015 | 01:35 PM
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You could shoot the thermostat housing with an infared temperature gun or get a scan tool that will display the coolant temp to see if its up to temp.

The EATC (E-lectronic A-utomatic T-emperature C-ontrol) HVAC system has a temp sensor that automatically swings the blend door to control the set temp. That sensor could be out of spec and its turning the heat down. There is a self test feature you can invoke to make the EATC do a self test of itself. (I just have to find my cheat sheet on how to trigger the self test.)
 
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Old Dec 30, 2015 | 02:44 PM
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The EATC (E-lectronic A-utomatic T-emperature C-ontrol) HVAC system has a temp sensor that automatically swings the blend door to control the set temp.
It has an actuator that moves the blend door, not a sensor.

It also has a sensor that checks the temp of the cabin air. The EATC uses that sensor to determine how much to drive the actuator and blower.

It's time to run the EATC self-test (google it) and see if the EATC is registering any faults.
 
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Old Dec 31, 2015 | 10:28 AM
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Here is the self test procedure and trouble codes.
 
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Old Dec 31, 2015 | 12:30 PM
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Originally Posted by alloro
Here is the self test procedure and trouble codes.
Good job! And many thanks...............
 
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