07 F650. The air conditioning and heater fan is intermittent, no rime or reason for when it works. Replaced the fan and the resistor and the the electrical plug to the resistor. Still some times it will work and then not. Does anybody know what I should replace next???

 

Can it be a grounding issue ? Did you try spraying some electrical contact cleaner onto the switch contacts ?

 

Thanks for the info. Not sure if it's a ground or contact issue. I'm wondering if it has something to do with the computer? My wife said she turned the key on a couple of days ago and the fan was working, but tried yesterday and it wasn't. So weird... thanks NoFrod for the reply.... David