Having issues w/ blower fan, help please, winter is comin

[gattaca37]

I have a 96' f250 pstroke auto that is having issues with the blower fan, the climate dial and heater/ac switch (dial) works fine. There are days that I will start truck (after sitting all night) and turn on blower fan and there will be no power to fan. Truck runs for 20-30 minutes and then blower fan turns on. There are other days where turn on truck (after she sits all night), and the blower fan works fine (has power). Fuses are all good. I pulled apart panel and pulled plug from blower switch and checked with test light. Sometimes there was power and sometimes no power (i am grounded to neg on battery). I also replace the blower fan switch (no luck, cause there was no power coming through harness).

I have power to blower fan and fan works (Check w/ test light and hooked up fan to battery). Trying to figure if there is a short in wiring harness, loose power wires, A relay getting hot and resetting itself (which relay, if it is a relay), or is there a loose ground wire. Anyone ever had this problem and what could be the cure for the curse? Thanks for the help cause winter is coming here in Michigan someday soon, John

[gattaca37]

anybody have any thoughts on this issue?

[Chop]

You might check the little risistor thingee that screws into the evaporator box,I think it has three large wires.This is what controls the fan speeds.Easy to remove and once you see the back side it will all come to you.Hope this helps