Q: Heater fan seems to surge

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Heater sounds like its surging. Already had thermostat replaced, and had blower resister replaced. Fan steel seems to rev up and slow down every 15or 20 seconds. Does this vehicle have an air mixer door that is vacuum operated? Kind of hear a door opening and closing. Help, tired of paying for non fixes.😞

My car has 176400 miles.
My car has an automatic transmission.

Hello. Your vehicle does use a vacuum operated heater control valve to allow hot coolant into the vehicle’s heater core so that warm air can be generated. If you hear an opening and closing sound then it may be possible that you are hearing the heater control valve work. Another possibility for that sound is the blend door actuator, which is the component that controls the temperature of the air coming out of the vents. If the heater sounds like it is surging then it could be possible that the vehicle is experiencing some sort of issues with the blower motor or blower motor circuit, perhaps the noise is coming from the motor itself. Similar symptoms can also be caused by an issue with the vehicle’s electrical system, perhaps a faulty alternator or an issue with the blower motor circuit. As potential electrical problems such as these can sometimes be difficult to diagnose, I would recommend having a professional technician, such as one from YourMechanic, visit your location to diagnose what may be causing your issues.

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