Range Hood: Fan turns on by itself

Some models of range hoods have a sentry feature that monitors the air temperature above the cooktop. If the temperature gets hot enough to trip the sentry system, the exhaust fan turns on to cool the cooktop area.

If the range hood fan turns on when the cooktop area is at room temperature, a failed temperature sensor, loose wiring or electronic control board failure could be the cause.

The sentry system uses a temperature sensor to monitor air temperature. If the fan turns on when the area above the cooktop is at room temperature, test the temperature sensor by checking its resistance using a multimeter. Refer to the range hood’s tech sheet or technical data for a temperature/resistance chart and replace the temperature sensor if its resistance doesn’t match the expected resistance shown on the tech sheet. If the temperature sensor’s resistance is okay, check the temperature sensor wiring connections and reconnect any loose wires. If wiring connections are okay, you likely need to replace the electronic control board because the control board isn’t detecting the temperature sensor’s signal correctly.

These repairs may help solve your Range Hood problem:

Replace the range hood temperature sensor

Sentry system

Some range hoods have a sentry system that monitors the air temperature above the cooktop. A temperature sensor mounted in the range hood measures that air temperature. If the sentry feature turns on when the cooktop area is at room temperature, the sensor could be defective. Replace the temperature sensor if it isn’t measuring the temperature properly.

For manuals, repair guides, and specific part recommendations, enter your model number.

Replace the range hood electronic control board

Electronic control board

The electronic control board operates the exhaust fan and cooktop lights in the range hood. If the electronic control board is getting power but won’t activate the fan or lights, replace it. The electronic control board also operates the sentry system on models equipped with that feature. Replace the electronic control board if it isn’t operating the sentry system correctly.

For manuals, repair guides, and specific part recommendations, enter your model number.