does anyone know what the little terminal is behind the glovebox on the upper/inner firewall?It exceptes the plug from my fan switch,but its blind in the engine bay.I have no power to the fuse for the fan either.Everything else is working so its not the ignition switch.I dont know where the thermo resistor is for the switch

 

That is a resistor for the fan speed's

 

diesel chassis.pdf

 

this info is sketchy at best iam using the the wiring diagram from a w 150 andits the closest i could come up with it says your resistors or on the right side of the dash on top of the heater assembly and the power wire comes to the fuse box directly from the ignition switch could be a bad wire or bad connection in the ignition switch and it says the color of the wire is light blue

 

yah Brown/blue off the fuse, the light blue goes to the ignition the brown goes to the switch,then back out with the other wires(switch positions) to the resistor,which is a bulkhead connection by the way.Its above the hvac box on the inner firewall.Pop your glovebox and have a look.