Hello All! new to this forum as this is my first post.

My blower fan speeds 1-3 stopped working on my 06 F150. Full speed was working fine.

Bought a new resistor switch off amazon:
Plugged it in and all speeds were working fine for maybe a couple minutes but then it stopped working again. 1-3 nothing, full blast still works.

I couldn't find an electrical diagram online to test continuity or resistance. Does someone know off hand, or would someone be able to test their working resistor, to give me the proper resistance values? There's 4 prongs on the resistor for me to test continuity but I have no clue which should be connected and which shouldn't be.

If it's not the resistor what else could it be, what should I test for?

 

Common ohmmeter lead to pin #2, readings should be +/- ~15%:

Pin 2 - Pin 1 - ~0.9 ohms
Pin 2 - Pin 3 - ~0.3 ohms
Pin 2 - Pin 4 - ~2.3 ohms

If all show open circuit, the thermal limiter has failed and the resistor module must be replaced.

The reason that HIGH works is that the resistor assembly is completely bypassed in that position and full battery voltage is applied across the blower motor terminals.

Check the switch for burned or damaged contacts while you're at it.

 

Here's a link to a new OEM part, Yes I'm here to sell parts but I've always found in my own vehicles that you typically can't beat OEM quality.

http://www.tascaparts.com/oe-ford/3f...=3F2Z*18591*AA

-Steve


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Would the resister cause the fan to blow porly on #2 but still work on #3 and #4

 

Possibly. The switch and the harness can also cause that symptom.