Your car's cabin fan (the blower motor) is a simple electric motor. To give you different fan speeds, the car can't just change the motor. Instead, it uses a blower motor resistor. This is a small electrical component with several coiled wires, each with a different amount of electrical resistance.
The resistor coils get very hot as they resist the flow of electricity. They are usually mounted inside the air duct so that the airflow from the fan itself keeps them cool. Over time, this constant heating and cooling causes the delicate coils to fatigue and break. When a coil for a lower speed burns out, that speed stops working.
The "fan-only-on-high" problem is a perfect example of a symptom that points directly to a single, specific part. Understanding that the blower motor resistor is the culprit saves diagnostic time and gets you straight to the solution. For Singaporean drivers in Malaysia, it's a relief to know that this common annoyance is typically a quick and inexpensive fix for a professional service like MyMechanic.
Don't suffer in the heat with a single fan speed. For Singaporean drivers in Malaysia, MyMechanic provides on-site diagnostics for all your A/C and electrical needs. We can quickly identify a failed blower resistor and advise on the simple replacement to restore comfort to your cabin.
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