Replace the blower motor resistor. It controls the 3 lower speeds. The reason high works is it does not use the resistor. They are around 20 bucks if I remember correctly and it is located in the black air duct on the passenger side almost far right. You can get to some of the screams easier if you take the glove box out. I think there are 4 or 5. It's easy. Should take 15 minutes. I bought mine at NAPA and it has about a year on it and still going strong.
When successive failures of fan speed controls start occuring, like first the resistor pack & then the switch, I have to think the root cause is the motor has gone bad & is drawing excessive current. The motor is supposed to draw something like 14-15 amps but once it starts going bad, it will start drawing over 20 amps. I'd be thinking you're probably also facing a new HVAC fan motor. The good news is the fan can easily be replaced from the engine side of the firewall. Closely examine the wiring harness between the switch & resistor pack too, it normally overheats when the fan motor goes bad & the insulation starts melting through causing more problems.
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