If there is a burning smell and my AC only works on number 4 do I have to replace both the blower motor resistor and the transistor? What happens if I only replace the transistor?
Your car is not equipped with a transistor for the blower motor. Your car has a blower resistor that controls the speed of the blower motor with the changes to the blower switch. The burning smell you are getting may be a combination of the blower motor going bad and overheating the blower resistor that is mounted in blower case next to the blower. I would recommend having the blower motor and resistor replaced.(https://www.yourmechanic.com/services/heater-blower-motor-replacement) Make sure to inspect connections at both of these components for heat related damages. Replace any melted connections with the component.
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