Front blower not working

I own a 99 Suburban 1500 5.7. The front blower motor stopped working on all speeds so I replaced the resistor, it still did not work. I then replaced the speed selector switch and it started working fine. Three days later I smelled a slight electrical burning smell and the fan stopped working again. I plan on replacing the switch again to see if that is what went bad. Any thoughts on whats causing this to happen? Maybe the motor is going bad and causing the switch to short?

Next time it is inop- meerly whaaaaap the blower motor on its housing- if it starts (it probably will) then the blower motor is worn out- anytime blower is inop on all speeds- do the whaaaaap test. Blower armature goes off center due to wear- and lands in a dead spot- whaaaaaping it- moves it back on center and it runs- until it lands in that dead spot again....

same thing works with starter motors and fuel pumps....

Thanks for the information but hitting the motor did not work. Correct me if I'm wrong but if the new speed selector switch works, maybe the motor is going bad and causing the switch to burn out?

Well, then put a test light or a volt meter on the leads to the blower motor- with it plugged in-- if you have juice, then bum blower motor...

I will go buy a test light. Can you recommend one? Also what wire do I test it on? The purple one?

Two wires feed blower motor- black is ground, purple is hot- test across these two- if nothing, then either a bad ground or bad source.

I will go buy a test light. Can you recommend one? Also what wire do I test it on? The purple one?

They're typically under $10. Think of a clamp lead, a light bulb, and an awl; the light bulb lights when the clamp is connected to ground, and the point touches positive voltage. A DC voltmeter (or multimeter) can do the same thing.