Downdraft Ventilation System: Goes up and down continuously

Problems with the vent limit switches or the up/down activation switch can cause the downdraft vent to move up and down continuously.

Limit switches detect when the vent reaches the upper and lower travel limits. If one of the limit switches breaks, the vent will raise and lower continuously. Disconnect electrical power to the downdraft vent and test continuity through the limit switches using a multimeter. Replace a limit switch if you measure the same continuity through a limit switch when the switch is activated and deactivated.

If the limit switches are okay, check the position of the up/down activation switch with power to the downdraft blower still disconnected. The vent must be in the raised position to check the activation switch, so lift the vent if it's in the down position and tilt it slightly so it stays raised. Remove the switch cover from the right end of the vent. Check the position of the up/down activation switch plunger. If the up/down button pad constantly presses down the plunger, loosen the up/down activation switch mounting screws and move the switch down until the bottom of the button pad membrane barely touches the plunger. Tighten the up/down activation switch mounting screws and replace the switch cover.

If the up/down activation switch position is okay, check continuity through the switch using a multimeter with electrical power disconnected from the downdraft vent. If the meter measures near 0 ohms of resistance with the switch plunger released, replace the up/down activation switch because it's letting current flow to the vent gear motor constantly, making the vent constantly move up and down. The up/down activation switch should stop current flow to the vent gear motor when the up/down activation switch plunger is released.

downdraft ventilation system

These repairs may help solve your downdraft ventilation system problem

Replace the downdraft limit switches

Replace the downdraft limit switches

If one of the two limit switches has failed, the pop-up vent will go up and down continuously. Replace the limit switch assembly.

Replace the downdraft up/down switch

Replace the downdraft up/down switch

If the pop-up vent will not raise or lower when the up/down button pad is pressed, the up/down switch may need to be adjusted. If the up/down switch is positioned properly and the button pad is pressing the up/down switch properly, replace the up/down switch.

November 1, 2015
By Lyle Weischwill
How to replace a downdraft vent up/down switch

When a downdraft vent won't pop up or retract, the up/down switch could be the problem. This step-by-step repair guide and video show how to replace a downdraft vent up/down switch in just 15 minutes or less.

Repair difficulty
Time required
 15 minutes or less
Read more

Symptoms common to all downdraft ventilation systems

Choose a symptom to see related downdraft vent repairs.

Main causes: lack of electrical power, up/down activation switch failure, bad vent gear motor
Main causes: fan control switch failure, bad blower fan motor, broken blower wheel, wiring failure
Main causes: electrical power failure, up/down activation switch problems, vent gear motor failure
Main causes: problems with the vent limit switches, up/down activation switch failure
Main causes: clogged grease filters, air duct problems, fan motor failure, broken blower wheel

Repair guides common to all downdraft ventilation systems

These step-by-step repair guides will help you safely fix what’s broken on your downdraft vent.

How to replace a downdraft vent up/down button pad

The up/down button pad located on top of the air vent engages the activating switch when pushed to raise the air vent. Replace the up/down button pad if damaged.

Repair difficulty
Time required
 15 minutes or less
November 1, 2015
By Lyle Weischwill
How to replace a downdraft vent gear motor

The gear motor raises and lowers the air vent when you push the activating switch. Replace the gear motor if defective.

Repair difficulty
Time required
 15 minutes or less
November 1, 2015
By Lyle Weischwill
How to replace a downdraft vent blower motor

The blower motor spins the fan blade that removes smoke and steam from the cooktop area. Replace the blower motor if it doesn't run when activated.

Repair difficulty
Time required
 30 minutes or less

Articles and videos common to all downdraft ventilation systems

Use the advice and tips in these articles to get the most out of your downdraft vent.

April 17, 2019

Downdraft vent common questions

By Sears PartsDirect staff

The most commonly asked questions about downdraft vents are answered by our experts.

January 18, 2016

How to use a multimeter to test electrical parts video

By Sears PartsDirect staff

Learn how to use a multimeter to check for wiring problems in an appliance that's not working

December 2, 2015

Wiring schematic symbols explained video

By Sears PartsDirect staff

Learn some of the most common symbols found in a wiring diagram and what they mean.