Hvac (AC) wiring diagrams

2014 FORD F-150
80,000 MILES • 3.5L • 6 CYL • 2WD • AUTOMATIC
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LEE1977
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AC blower does not work on max speed. New resistor, motor and cable. Works on all other speeds. When max speed is selected, it blows for a moment and shuts off until a lower speed is selected. Old resistor had signs of overcurrent on one of the pins. That is why I replaced all components. System used to shut off at all speeds. Now, just highest setting fails.
Aug 7, 2018 at 5:28 PM
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STRAILER
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Hello,

It sounds like the HVAC control head is losing signal, but to be sure here are the wiring diagrams so you can see how the system works and a guide on how to test it. If it tests bad I would try a used control head so you might need not to reprogram it. If so it will cost about $130.00 at the shop. Also, when you say resistor you mean the motor speed control? Were the parts OEM?

https://www.2carpros.com/articles/how-to-check-wiring

Check out the diagrams (below). Please let us know what you find.

Cheers, Ken
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Aug 9, 2018 at 3:19 PM
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LEE1977
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No, parts were O'Reily. Yes, by resistor, I mean the motor speed control.
Aug 9, 2018 at 4:28 PM
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STRAILER
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It sounds like the speed controller is out again so you may have got a bad one. Try to take it back and if the new one works then you know what the problem is.
Aug 10, 2018 at 10:55 AM
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LEE1977
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Replaced the resistor again today (third time) and the problem still exists. Although, I may have narrowed it down. It only shuts off when the recirc is on at the highest setting. Almost as though there is a restriction in the duct and it causes the blower to pull too many amps and trips.

If the recirc is off, the fan works on all settings.

Any thoughts?
Aug 12, 2018 at 6:58 PM
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STRAILER
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When the blower is on high and working can you feel the wires going to the blower motor to see if there are warm?
Aug 13, 2018 at 12:55 PM