Mechanics

THE REAR AC WORKS FINE. THE FRONT AC WORKS INTERMITTINGLY. COULD THIS BE A THERMOSTAT PROBLEM?

2004 Ford Expedition • 120,000 miles

Fan is set to "Auto" nothing happens, then suddenly, it turns on. Sometimes after an hour of driving
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GPC
June 29, 2012.




It is probably in the Automatic Temperture Control Board, I attached diagram so you can see blower motor controller is part of this circuit board.
So you will probably have to replace the controller and the blower controller wil be part of it. The other possiblity, although it would less likely explain the blower motor issue, is the interior temperature sensor. The diagram only shows one temp sensor so the seperate temperture function must be a logic function inside the circuit board. This again points towards the circuit board and not the snesor as the differnt temps when set at a temperture equal not working in different parts of the cabin is the job of the logic board.
Your best bet is to get a temp snesor and board from a salvage yard and replace the sensor first to make sure it is not affecting the logic function for the temperature in the cabin being different. The diagrams attached state the position of the sensor.




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