The AC/fan doesn't work on 1st speed (fan control knob). Looks like it's a common failure, anybody knows what part to replace ?

blower motor resistor failures are common, also melted blower motor resistor connectors

Are those resistor in the motor itself ? Is that a quick fix or if I can't do anything without replacing the motor ?

Resistor is near the blower motor, not a big job, its something that can be done if your handy type of person!!

With GM parts price, I learned to be handy pretty quick ah ah