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Q: My car won't reach full fan speed

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Hey there, having problems not reaching full fan speed on my 2007 GMC Sierra. On the display it gets every fan speed but the high speed one. Just wondering if you guys think it's the blower motor resistor or what it might be?

My car has 130000 miles.
My car has an automatic transmission.

Hello. A failed blower motor resistor will cause certain fan settings to fail. In fact this is the most likely cause for your symptoms. Accessing the motor can be the hardest part. You will want step by step guides to help you if attempting to DIY. Once you can visually inspect the resistor, you may find burn marks, or other types of deposits or damages. The only other typical malfunction that would cause this would be a switch malfunction. Even still, those chances are smaller. If you’d like assistance with this, consider having a certified technician, such as one from YourMechanic, diagnose the issue with your fan speed and help you make the necessary repairs.

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