Ok Gents here are the details:

-2003 F150 XLT FX4 Super cab 5.4L 4x4
-Manual A/C heat, 4 position fan speed switch

-symptoms:
the fan works both on heat and a/c, it also runs in all positions However in the position just before HIGH the speed varies. If I wiggle the switch the speed will pick up.

-I know 90% of the time the resistor can be the cause of issues with fan speeds, but this has me scratching my head. I am thinking it's the switch itself mainly because if I give it a wiggle it will go up to correct speed.

-What do you think?

 

Pull the switch out and inspect its connector. If burned/melted, replace both the switch and the connector pigtail. Same for the resistor.

If there is no evidence of overheating, replace the switch.