Q: A/C makes loud humming sound

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Yesterday my mechanic gave my SUV a full synthetic oil change, as well as a cabin air filter change. Now, today I turned on the A/C and there was a very loud refrigerator humming sound that was coming from the dash/engine. Or perhaps more like a truck vrrrrrrrrrr sound. I don’t do any of my own repair work. Everything has been dealer serviced. My SUV makes this sound when the ACC mode is on, without the compressor running, as well as when the compressor is on. There is also a fluctuation in the volume of the fan speed - higher speeds of the fan produce louder sound and the lower fan speeds produce more quiet sound. In your assessment, what will fix this?

The blower fan motor has something caught in it or the air filter is not in position and hitting the blower fan. Have the person or shop that did the work fix it. The filter may be out of position or was not seated properly and should be fixed to prevent blower motor damage. If you want to have an independent mechanic take a look at this, a technician from YourMechanic can come to your home or office to diagnose your car’s noise and make any needed repairs.

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