Heater blower motor started to quit a couple of times a day

To begin with..... HVAC/heater blower motor started to quit a couple of times a day, then quit completely. Installed new blower motor and new resistor... It worked for about a week and started the same thing again. Took back blower motor and resistor and exchanged for new parts again, and installed them.
Same thing... Sometimes driving down the road, the blower would come on again for a while. Never seemed to be anything specific that I did that would start it up again. (Always left it set on high)
I was told to replace blower relay which I did a couple of times. But then I found your answer, on “just Answer”, to another person’s similar situation, (posted on your website on 12/21/2010) and found out that my truck does not use a blower relay, but feeds directly off of ignition switch.
So good to know! Thanks

To date I have replaced new, in the past couple of weeks;
• Blower motor
• Resistor
• Ignition switch
• Multi-function switch (twice, new switch had problem with hi-beams)
• Battery (twice, 1st new battery had dead cell)
• Fuses
• Alternator
• Alternator 140 amp fuse
• Cable from alternator to under-the-hood fuse box
• Both battery cables
• Checked well for any signs of burnt or melted connections during all installations.
Also, even when truck is off, no key in ignition, flasher for turn signals keeps clicking. I can turn emergency flashers on and off, it stops momentarily sometimes, sometimes over night.

I have power on the big red wire and the big green/black wire, the blue wire, and the yellow wire at the new ignition switch. No power on fan speed switch. Power only on small blue wire at the fan /resistor connector. No power on anything else at that fan/resistor connector. No blown fuses and power at fuse blocks to each fuse.