Discovering that your dryer will not turn off can be alarming and potentially dangerous. If opening the dryer door stops the dryer, it indicates that the door switch is still working correctly, but a problem likely exists with the motor relay on the control board. Other less common causes of the issue include the anti-wrinkling feature being enabled or the start button being stuck.
Fortunately, with this guide to help, you should be able to fix the issue without needing to call a trained technician.
With dryers that have an anti-wrinkling function, such as Samsung’s Wrinkle Prevent, if the feature is enabled, the drum will continue rotating for a few minutes when the dryer completes the cycle, then it will switch to rotating the drum intermittently. The dryer may not stop this process until the dryer door is opened. If you want your dryer to stop after a cycle, turning off the anti-wrinkling function should solve the issue.
The motor relay
The most common reason for a dryer stopping only when the door is opened is that the motor relay on the control board is stuck or has shorted out. When the motor relay is stuck in the “on” position, the control board signal to stop the dryer is ignored, which results in the dryer staying on when it should turn off. To find out if the motor relay is damaged, the dryer’s control board needs to be examined.
How to access the control board:
- Disconnect the dryer from the power source.
- Move the dryer to access the main control board behind the control panel.
- Remove the screws that hold the control panel in place.
- Remove or tilt the control panel to access the control board.
- Locate the motor relay switch on the control board. The relay is usually a black, rectangular box.
- Examine the control board for damage.
If there are black marks, burnt pins, or melting on the control board, the start relay will need to be replaced.
If you discover a damaged motor relay on the control board, it can be replaced if you have access to a soldering iron and know how to solder electrical components. If you do not want to use a soldering iron, the entire control board can be replaced instead, as it comes with a new motor relay already attached.
How to remove the control board
To replace the relay or the control board, you will need to remove it from the dryer. The control board may be secured to the dryer with locking tabs and/or a screw. Some dryer models may have a dust cover over the control board. The cover can usually be removed using a Phillips-head screwdriver to remove the screws that secure the cover. The locking tabs can be released by pushing them to the left with your fingers, and the screw securing the control board can usually be removed with a Phillips-head screwdriver.
The electrical connectors plugged into the control board also need to be removed. With most dryers, the connectors can be disconnected by hand without much difficulty. However, make sure you note down or take a picture of where the connectors are plugged in so that you know how to reconnect them when reinstalling the control board.
How to replace the motor relay (requires soldering)
Once you have removed the control board from the dryer, a soldering iron can be used to replace the motor relay.
- Use the soldering iron to heat the pins on the back of the relay.
- While melting the solder, carefully remove the relay from the control board.
- Tidy up the holes in the control board so that the pins from the new relay can fit through.
- Position the new relay on the control board so that the new relay’s pins go through the holes in the board.
- Heat the pins with the soldering iron and touch the solder onto it.
The new motor relay should now be attached to the control board, and the control board can be returned to the dryer. After you have secured the control board and reconnected the wire connectors, reassemble the dryer’s control panel. After you have put the control panel back and reconnected the power, test the dryer to see if the issue has been resolved. If the issue persists, you should replace the entire control board.
How to replace the control board
If you are unfamiliar with soldering and want to replace the control board to fix the issue, installing a new control board is relatively easy. When purchasing a new control board, make sure the replacement board is correct for your brand of dryer by matching the model number. Follow the steps above for removing the old control board and installing the new one.
The start button is stuck
A less common reason for the dryer turning off only when the door is open is if the start button is stuck. If the start button is stuck, it will constantly send power to the dryer motor, which means it is only when the dryer door is open that the door switch cuts off the power. Inspect the start button to determine if it is stuck. If the button is stuck, try jostling it to cause it to release. If this doesn’t work, it will need to be repaired or replaced.
A dryer that will not turn off unless the door is open almost always has a defective motor relay. However, before replacing the motor relay or the entire control board, check whether the anti-wrinkle function is enabled or the start button is stuck, as these are easier issues to deal with.