1999-2007 General QuestionsGeneral questions related to 1999-2007 Super Duty trucks. If it doesn't fit the other categories, post it here. Gas engine discussion that pertains to all models is allowed. Specific gas engine questions should use the Gas Engines forum.
I guess I could let you read the title and guess, but since I need help, I'll provide more information.
2006 F350 Electronic Automatic temperature control. 142.000 miles.
FICM was bad. Low voltage and all of that. While testing, I noticed that the heater blower was on full speed and I couldn't shut it off even with the main EATC controller switch turned off and the display blank. hmmm That's odd.
New case half and it starts and runs fine, but the blower is still on full speed. I checked codes in the EATC controller and nothing is there. It passes KOEO tests.
I can watch the switches with my scanner and everything works... Well, not quite. I can press the fan speed on the dash and the scanner shows the button pressed up or down, but if I push the button on the steering wheel, the lines go up and down on the display, but the scanner doesn't show the switch pressed. To me, these two things contradict each other.
When doing tests with the scanner, the blower motor will shut off until I do the test. When testing fan speed with the scanner, the speed stays the same: full speed ahead, regardless of what % it should be at.
I can pull the heater motor relay and the motor shuts off. There is always battery voltage at the signal wire on the relay. The relay puts power to the motor, then the speed controller controls the ground for the motor. If there is a short to ground between the motor and the speed controller, that would give us full motor speed all the time, but, A: how likely is that, and 2: where is the speed controller located in this truck, and 3: why is there power to the relay all the time the key is on?
Hopefully someone has run into this and I just didn't find anything while searching.
That's the resistor block. Typically when that goes bad, you loose speeds, with typically only high speed working and if you switch to any other speed, the blower turns off. Maybe this one fails differently, because that isn't what is going on.
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