Totally Baffled - HVAC

Several years ago, the 'spindle' on my blower control switch on my 2001 E150 XLT Club Wagon got so damn hot it nearly melted the knob....and its harness. I replaced the blower control switch last year. Same problem resurfaced. I have now replaced the blower fan, the control switch and its harness....and the damn spindle gets extremely hot after about 15-20 minutes? The only component I have not changed is the blower relay. I have to continually check how hot the spindle is and, if hot, turn off the fan. Other than this, everything works fine - all blower speeds, vents, A/C.


I am at a loss!!! No where on the Internet can I find similar experiences.


Please help!