Some will tell you that if the blower motor speed control module (resistor) failed, then it should still work on full blast. The module increases ground resistance to slow the fan motor to slower speeds than full blast. But it depends on how the resistor failed. My fan wouldn't come on at all. Full blast, lower speeds, nothing. The module is a black box in the engine compartment mounted to the firewall, right next to the heater core supply and return hoses. a bit of a pain, but not too bad. Had to pop off one heater hose, only a few drops leaked out. Took about an hour.
https://www.rockauto.com/en/catalog/...+resistor,6557