How to Replace a Downdraft Vent Fan Control Switch



This DIY repair guide explains how to replace a fan control switch on a downdraft vent. Located on the upper right side of the vent, the fan control switch activates the blower fan motor and controls the blower speed. If the fan control switch wears out or breaks, it won't start the fan motor or control the speed. Replace the fan control switch with the manufacturer-approved replacement part.

This repair guide and video shows how to replace the vent fan control switch in Kenmore and Broan downdraft vents.

Repair difficulty:
Time required:

Less than 30 min.

Parts Required

  • Fan Control Switch

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

Tools Required

  • Work gloves
  • Phillips screwdriver
  • Wire cutter
  • 1/4" nut driver

Before you begin

Wear work gloves to protect your hands. Unplug the cooktop and the downdraft vent. Remove the cooktop from the counter. Remove the downdraft vent from the counter and lay it down on a padded work surface.


 Warning: Undertaking repairs or maintenance to appliances or power equipment can be hazardous. Should you choose to undertake repairs or maintenance, you are assuming the risk of injury to your person or property. In an effort to reduce the risk, use the proper tools and safety equipment noted in the applicable guide and follow all instructions. Do not proceed until you are confident that you understand all of the steps and are capable of completing the repair. Some repairs or maintenance, however, should only be performed by a qualified technician.

How to Replace the Fan Speed Control Switch in a Downdraft Vent

Step 1: Remove the gear motor cover

With the power disconnected, remove the mounting nuts from the clamp channels and then remove both clamp channels.


Remove the screws from the gear motor cover.


Disconnect the gear motor wires and then remove the gear motor cover.

Step 2: Remove the blower housing assembly

Carefully tilt the top of the blower housing up and disconnect the blower motor wire harness.


Remove the blower housing assembly.

Step 3: Remove the air box cover

Remove the mounting screws from the air box cover and pull off the air box cover.

Step 4: Disconnect the fan control switch wire harness

Unplug the wire harness for the fan control switch.


Cut the wire tie that secures the fan control switch wire harness to the green ground wire.

Step 5: Raise the air vent

Pull the air vent up to access the fan control switch.

Step 6: Remove the switch cover

Remove the mounting screws and pull the switch cover off.

Step 7: Pull out the switch bracket

Remove the screws from the switch bracket.


Slide the switch bracket downward and then pull the bracket out.

Step 8: Remove the fan control switch

Pull the knob off the fan control switch stem.


Remove the fan control switch mounting nut.


Pull the fan control switch out of the switch bracket.


Disconnect the up/down switch wires.


Cut off the wire tie from the switch bracket to release the fan control switch wires.


Remove the fan control switch.

Step 9: Install the new fan control switch

Connect the up/down switch wires.


Secure the fan control and the up/down activating  switch wires to the switch bracket using a wire tie.


Reinstall the fan control switch on the switch bracket and secure it using the mounting nut.


Reinstall the fan control knob on the stem of the fan control switch.

 Tip: There are no threads on the plastic stem of the new switch. Thread the nut straight on and it will create its own threads.

Step 10: Reinstall the switch bracket

Slide the switch bracket into the vent and reinstall the bracket screws, leaving the screws loose.


Adjust the switch bracket so that the activation switch lightly touches the membrane pad.


Tighten the bracket screws firmly.

 Warning: Don't pinch any switch wires when installing the switch bracket.

 Tip: Mounting the switch bracket up too high will keep the switch depressed and the vent will raise and lower continuously when you restore power.

Step 11: Reinstall the switch cover

Reinstall the switch cover and secure it using the mounting screws.

Step 12: Lower the air vent

Push the air vent down into the air box.

Step 13: Connect the fan control switch wire harness

Plug in the fan control switch wire harness.


Connect the fan control switch wire harness to the green ground wire using a wire tie.

Step 14: Reinstall the air box cover

Position the air box cover over the air box and thread the gear motor wires through the grommet in the air box cover.


Secure the air box cover to the air box using the mounting screws.

Step 15: Reinstall the blower housing assembly

Position the blower housing assembly on top of the air box cover.


Tilt the blower housing assembly up and plug in the blower motor wire harness.


Lower the blower housing assembly into place.

Step 16: Reinstall the gear motor cover

Thread the wires through the gear motor cover and reconnect the wires to the gear motor.


Position the gear motor cover over the gear motor and reinstall the mounting screws.


Reinstall the clamp channels and secure them using the mounting nuts. 

Step 17: Reinstall the downdraft vent and cooktop

Reinstall the downdraft vent and cooktop in the counter following the directions in the installation guides.

Step 18: Restore power

Reconnect the power cords for the downdraft blower and the cooktop.