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What does the final stage resistor do?
The blower final stage fan resistor also goes by the name of the blower motor resistor. This component is an electrical part responsible for providing the voltage to the fan that controls the heating and air conditioning in your BMW. You can find a blower motor resistor in BMWs that have 4 or 5 fixed speeds.
How does a blower motor resistor work?
The blower motor resistor is responsible for controlling the blower motor speed. In the past, this was done by varying the voltage supplied to the blower motor. In newer applications, the blower motor resistor is actually a solid state module that sends a varied signal to the blower motor.
Can you repair a blower motor resistor?
The resistor module is easy and inexpensive to replace. It’s then typically installed in the ductwork, near the car blower—either under the dash or under the hood. (Refer to a service manual to locate yours.) Purchase a new resistor module at the auto parts store (usually less than $25).
What happens when a resistor fails in a circuit?
Resistors rarely fail when the circuit is designed properly, but under overload conditions (such as the failure of a component elsewhere in the circuit that puts a high voltage across the resistor) resistors typically fail by becoming an open circuit (after becoming very,…
What causes a carbon film resistor to fail?
Carbon film and composition resistors can fail (open circuit) if running close to their maximum dissipation. This is also possible but less likely with metal film and wirewound resistors. There can also be failure of resistors due to mechanical stress and adverse environmental factors including humidity.
What causes a wirewound resistor to fail?
There can also be failure of resistors due to mechanical stress and adverse environmental factors including humidity. If not enclosed, wirewound resistors can corrode. Variable resistors degrade in a different manner, typically involving poor contact between the wiper and the body of the resistance.
Can a thin film resistor be damaged by high voltage?
Low-power thin-film resistors can be damaged by long-term high-voltage stress, even below maximum specified voltage and below maximum power rating. This is often the case for the startup resistors feeding the SMPS integrated circuit. When overheated, carbon-film resistors may decrease or increase in resistance.