1999 Explorer Fan switch only works on High

[BillRod]

Hi All

Fan switch only works on High in my 99 Explorer.
Is that usually the switch itself or is there a controller or relay or something else that might be causing it.

Thanks in advance!
Bill

 

[RonD]

Issue is the Resistor Block
This controls lower fan speeds, resistor block is by-passed for HIGH speed
Its in the engine bay on the heater/AC/blower box

Looks like this: https://contentinfo.autozone.com/znetcs/product-info/en/US/wl2/JA1652/image/2/

Can be grey or black, the heat sink(fins), are inside the air box to cool them so you just see the connector and the two screws holding it to the air box
Should have 4 or 5 wires

 

[don4331]

The Resistor block is set in airflow, so it gets cooled when fan is running, but it is also in the path for condensation when SUV is turned off. So, the "speeds" wires corrode and fail over time.

Replacing the block in the engine compartment (firewall, passengers side) fixes issue 99% of time.

 

[BillRod]

Awesome! Thank you guys!
Would you happen to have a pic of what it looks like from the engine bay?

Thanks again!
Bill

 

[scotts90ranger]

If you open the hood, stand on the passenger side, look down at the hood hinge area you'll see the heater blower motor, the only other thing on the blower housing just below and further toward the engine on the blower housing is the resistor pack (has one connector on it and one screw/bolt holding it to the housing if memory serves). There's two types, one that is an actual electronic speed control and one that is just resistors... basically if you have rear climate control you have the fancier one that is like $100 versus the one that's like $20... when the one in my '00 Explorer went out I went to the junkyard and grabbed one. Oh, and of course there's two different connectors, it's been 4 years or so since I did mine so I don't remember the differences but I think the year breaks are '95-97 and '98-01? I have a '98 Eddie Bauer, a '00 Limited and a parts '97 Mountaineer, I can take pictures (it's 90F outside right now so not now...) if needed...

 

[RonD]

Its a bit of a PITA on Explorers vs Rangers

Google: How to Replace Blower Motor Resistor 95-01 Ford Explorer

Watch the 8:49 video
Not sure you can get at it without all those steps of removing the blower motor
But you are there, so can look and see