The problem of blower motor resistors is common in many cars. The most common symptom of a blower motor resistor is that the heater fan only runs at the highest speed setting (4 or 5) and does not work at low speeds. In some cars, the blower motor resistor failure can cause the heater fan to stop working completely.
In most cases, the car blower motor resistors fail due to corrosion or overheating. Sometimes, the mechanical resistance to the rotation of the motor can cause excessive current, which can overheat and prematurely damage the blower motor resistance. This can happen, for example, when the fan blades are stuck by foreign objects or the motor bearings are worn out and cannot rotate freely.
The blower motor control module has a lower frequency of problems, but it fails for the same reason: failures caused by corrosion or overheating when the motor is stuck or short-circuited. In most cases, when the blower control module fails, the auto ac blower motor does not work at all. In some cars (for example, older GM trucks), even if the ignition switch is turned off, a blower control module or processor failure will cause the blower motor to continue to run.
Post time: Jun-29-2020