Range vent hood turning on by itself: Common Causes & How to Fix
1Range Vent Hood Thermostat
Common Solution
Repair Instructions:
Some range hoods have a thermostat that turns on the fan automatically if the inside of the hood gets too hot. Check the owner's manual or wiring diagram for your model to see if it has this feature. If it does, the thermostat will kick the fan on when the temperature rises above a set point. This helps cool down the hood until it reaches a normal operating temperature again. Once cooled, the thermostat will turn the fan off. This prevents the range hood components from overheating. Knowing if your unit has an automatic cooling fan will help troubleshoot ventilation issues. The manual or wiring diagram will show if there is a temperature-sensing thermostat that controls the fan based on heat levels inside the hood.
How to Replace Range Vent Hood Thermostat
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Turn off power and disconnect electrical supply - Locate the circuit breaker for the vent hood and turn it off. Disconnect all wiring to the thermostat.
- Remove access panel - Remove any access panel that provides access to the thermostat mounting.
- Detach wiring connectors - Disconnect the wiring harness connectors attached to the thermostat.
- Remove mounting screws - Remove the mounting screws securing the old thermostat.
- Remove old thermostat - Carefully maneuver the old thermostat out of the vent hood.
- Install new thermostat - Align and insert the new replacement thermostat into proper position.
- Replace mounting screws - Reinsert and tighten mounting screws to secure the new thermostat.
- Reconnect wiring - Reattach the wiring harness connectors to the new thermostat.
- Replace access panel - Replace any access panel that was removed from the vent hood.
- Restore power - Restore power and verify the new thermostat functions properly.
2Range Vent Hood User Control and Display Board
Common Solution
Repair Instructions:
The control board that operates the user display might be broken. But these boards are often thought to be bad when they actually work fine. Before replacing the user control and display board, first check the other parts that more often go wrong. Things like switches, sensors, wires and fuses should be tested first when there is a problem. That's because those cheaper parts fail most of the time, not the control board. Only replace the board if testing proves the switches, sensors, wires and fuses are okay. Jumping to replace the control board is expensive if it's not really faulty.
How to Replace Range Vent Hood User Control and Display Board
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Turn off power and disconnect electrical supply - Locate the circuit breaker for the vent hood and turn it off. Disconnect all wiring to the control board.
- Remove access panel - Remove any access panels from the vent hood to access the control board.
- Detach all wiring connectors - Disconnect all wiring harness connectors attached to the control board.
- Remove mounting screws - Remove any mounting screws securing the control board in place.
- Remove old control board - Carefully maneuver the old control board out of the vent hood.
- Install new control board - Align and insert the new replacement control board into proper position.
- Replace mounting screws - Reinsert and tighten mounting screws to secure the new control board.
- Reconnect wiring harnesses - Reattach all wiring harness connectors to the correct pins on the new control board.
- Replace access panel - Replace any access panels that were removed from the vent hood.
- Restore power and test - Restore power and test that the new control board functions properly.
3Range Vent Hood Control Board
Common Solution
Repair Instructions:
If testing shows the thermal fuse is okay and the control board is getting power, the control board may be broken. But these boards are often assumed faulty when they actually still work. Before replacing the range hood control board, check other parts that fail more often first. Things like switches, motors, capacitors, wiring and fuses should be tested before the board. That's because those cheaper parts usually go bad more than the board. Only change out the control board if those components check out fine. Jumping to replace the control board can be pricey if it's not really broken. Make sure to troubleshoot the other common problem parts first before deciding the control board needs replacing.
How to Replace Range Vent Hood Control Board
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Turn off power and disconnect electrical supply - Locate the circuit breaker for the vent hood and turn it off. Disconnect any wiring connectors.
- Remove filters and baffles - Remove any filters or baffles obstructing access to the control board.
- Detach wiring connectors - Disconnect all wiring harnesses and connectors attached to the control board terminals.
- Remove mounting screws - Remove the screws securing the control board to the vent hood.
- Remove control board - Carefully remove the old control board from the vent hood.
- Install new control board - Place the new control board into position, aligning any mounting holes.
- Replace mounting screws - Insert and tighten screws to secure the new control board.
- Reconnect wiring - Reattach all wiring connectors to the terminals on the new control board.
- Replace filters and baffles - Replace any filters or baffles that were removed.
- Restore power - Restore power to the vent hood.
- Test operation - Turn on the vent hood and test that the new control board is functioning properly.
4Range Vent Hood Touchpad
Common Solution
Repair Instructions:
If testing shows the thermal fuse has continuity and the touchpad control is getting electricity, then the touchpad is probably broken and needs replacing. Use a multimeter to check the thermal fuse for continuity. Also verify with a multimeter that power is reaching the touchpad when turned on. If those check out okay but the touchpad still does not work right, it will need to be swapped out. Get a replacement touchpad made specifically for your appliance model. Follow the wiring diagram carefully to connect all the wires when installing the new touchpad. This should restore proper function if the original touchpad was faulty.
How to Replace Range Vent Hood Touchpad
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Turn off power and disconnect electrical supply - Locate the circuit breaker for the vent hood and turn it off. Disconnect any wiring connectors.
- Remove mounting screws - Remove the small screws that secure the touchpad to the vent hood.
- Detach touchpad - Gently pry off the old touchpad from the vent hood. Take care not to bend or damage it.
- Disconnect wiring - At the rear, disconnect any wiring connectors attached to the touchpad.
- Attach wiring to new touchpad - Connect the wiring to the terminals on the back of the new replacement touchpad.
- Position new touchpad - Place the new touchpad into position on the vent hood, aligning any screw holes.
- Secure with mounting screws - Insert and tighten the small mounting screws to secure the new touchpad.
- Restore power - Restore power to the vent hood.
- Test operation - Turn on the vent hood and test that the new touchpad powers on and activates fan speeds properly.
- Reassemble vent hood - Replace any other components or covers that were removed during the repair.
5Range Vent Hood Main Control Board
Common Solution
Repair Instructions:
The main control board that operates everything could be broken. But these boards are often assumed bad when they actually still work. Before replacing the main control board, first check the other parts that fail more often. Things like switches, sensors, wires and fuses should be tested first if there's an issue. That's because those cheaper parts usually go wrong more than the control board. Only replace the board if testing shows the switches, sensors, wires and fuses are fine. Jumping to replace the control board is pricey if it's not really faulty.
How to Replace Range Vent Hood Main Control Board
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Turn off power and disconnect electrical supply - Locate the circuit breaker for the vent hood and turn it off. Disconnect any wiring connectors.
- Remove filters and baffles - Remove any filters, baffles or covers obstructing access to the main control board.
- Detach wiring connectors - Disconnect all wiring harnesses and connectors attached to the main control board terminals.
- Remove mounting screws - Remove the mounting screws securing the main control board to the vent hood.
- Remove main control board - Carefully remove the old main control board from the vent hood chassis.
- Install new main control board - Place the new main control board into position, aligning any mounting holes.
- Replace mounting screws - Insert and tighten screws to secure the new main control board.
- Reconnect wiring - Reattach all wiring connectors to the terminals on the new main control board.
- Replace filters and baffles - Replace any filters, baffles or covers that were removed.
- Restore power - Restore power to the vent hood.
- Test operation - Turn on the vent hood and test that the new main control board is functioning properly.
6Range Vent Hood Control Module
Common Solution
Repair Instructions:
The control module is the circuit board inside that runs the range hood fan and blower. If the control module breaks, it can make the fan not turn on. Some reasons it can fail: Power surges or spikes can harm its sensitive electronics. Long use over time can make its circuits and parts wear out or corrode. Grease and moisture getting in can cause electrical shorts. The touchpads connect to the module, so pressing them a lot can damage the controls. Individual parts like transistors or processors can also fail from age and stress. If the module is broken, it may not send the electric signal to start the fan when you try to use it. The fan needs that signal to run. So if the control module is faulty, the fan won't work even if the actual fan still can. Typically the bad control module needs replacement to make the range hood fan and blower work again.
How to Replace Range Vent Hood Control Module
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Turn off power and disconnect electrical supply - Locate the circuit breaker for the vent hood and turn it off. Disconnect any wiring connectors.
- Remove filters and baffles - Remove any filters, baffles or covers obstructing access to the control module.
- Detach wiring connectors - Disconnect all wiring harnesses and connectors attached to the control module terminals.
- Remove mounting screws - Remove the mounting screws securing the control module to the vent hood.
- Remove control module - Carefully remove the old control module from the vent hood chassis.
- Install new control module - Place the new control module into position, aligning any mounting holes.
- Replace mounting screws - Insert and tighten screws to secure the new control module.
- Reconnect wiring - Reattach all wiring connectors to the terminals on the new control module.
- Replace filters and baffles - Replace any filters, baffles or covers that were removed.
- Restore power - Restore power to the vent hood.
- Test operation - Turn on the vent hood and test that the new control module is functioning properly.
7Range Vent Hood Touchpad and Control Panel
Common Solution
Repair Instructions:
If testing shows the thermal fuse is working and the touchpad control panel is getting electricity, then the touchpad is probably broken and needs replacing. Check the thermal fuse with a multimeter to confirm continuity. Also use a multimeter to verify power is reaching the touchpad when switched on. If those check out okay but the touchpad still does not operate properly, it will need to be changed out. Get an identical replacement touchpad made for your specific appliance model. Carefully install it following the wiring diagram to connect all the wires correctly.
How to Replace Range Vent Hood Touchpad and Control Panel
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Turn off power and disconnect electrical supply - Locate the circuit breaker for the vent hood and turn it off. Disconnect any wiring connectors.
- Remove mounting screws - Remove the screws that secure the control panel/touchpad assembly to the underside of the vent hood.
- Detach control panel - Carefully lower the control panel/touchpad assembly down from the vent hood.
- Disconnect wiring - At the rear, disconnect any wiring connectors or terminals leading to the control board.
- Remove and replace touchpad - Take out the old touchpad from the control panel and replace it with the new touchpad.
- Reconnect wiring - Reconnect all wiring connectors and terminals to the control board.
- Reinstall control panel - Place the control panel assembly back up into position and replace the mounting screws.
- Restore power - Restore power to the vent hood.
- Test operation - Turn on the vent hood and test that the new touchpad and controls operate properly.
- Reassemble vent hood - Replace any other components or covers that were removed during the repair.