Article was written by Serge, appliance technician. Serge Appliance Repair (Ottawa, ON)
Samsung dryer won't turn off. Understanding the problem.
Samsung dryer won’t turn off and run anytime you close its door if there is a problem with the main board, PCB (relay board). This particular problem is a stuck motor activating relay. I investigate many other similar cases in this article, too, to understand all the possibilities we need for the best diagnostic of the problem. Nice reading!
To start the Samsung dryer, we push the POWER button, select the program and additional options, and hit the START button. Do we need to turn off the dryer? It will stop itself.
If you read this article, something goes wrong. You see that your dryer runs too long, and the clothes stay wet or get too hot. Or the dryer keeps running and doesn’t shut off unless you open the door.
There are four ways to get a Samsung dryer stop.
- A Normal way:) is to wait until the cycle is finished and the dryer stops.
- Use any buttons on the control panel: STOP, PAUSE, POWER.
- Open the dryer’s door.
- To cut the power – unplug the dryer’s electricity supply cord or turn off the breaker.
To understand the article’s main topic—the Dryer does not turn off unless the door is opened—I will discuss similar problems. In the first two cases below, you can stop the dryer using the control board buttons: STOP, PAUSE, and POWER.
The first case. The dryer doesn't stop because it can't finish the cycle (it is not drying = the clothes stay wet) .
I investigated this case in my article, “Is Your Samsung Dryer Not Drying? Here’s What You Need to Know.” There are multiple options. Sometimes, the problem is in the dryer, and sometimes, it is in the ventilation system.
The second case. The dryer doesn't stop, but the clothes are dry.
The dryer continues running even when the clothes are already dry. In this case, you should check two things:
1. A moisture sensor. This sensor has two bars (the picture is below) and wires conducting the signals to the electronic control. When the clothes are wet and touch the bars, an electric bridge is formed between them.
The dryer’s brain—the electronic board—knows that the clothes contain moisture, so it continues working to reduce it. However, if the sensor sends a wrong signal, the dryer may not stop, and the clothes will overheat.
It could be if the bars or wires are shorted, usually by objects and dirt. We must check the sensor’s bars for any damage and clean it from dirt.
2. The electronic board. The sensor is okay and sends the right signals, but the electronic board is wrong. This is a very rare case. Later in the article, I will explain how to check it.
The third case is the actual problem I am investigating in this article. The key sign is that you can’t turn the Samsung dryer off using the buttons from the user interface: STOP, PAUSE, POWER. But it stops when you open the door.
Go deep into the main topic.
Why the Samsung dryer won't turn off ?
The most common cause of this issue is a faulty power control board (PCB), but the user interface, door switch, heating element, and cut-off thermostat should also be checked thoroughly.
Electronic control board /user interface
The Samsung dryer has two control boards. The first is an electronic control board inside the control panel, which works at 12V. It is responsible for the user interface, including buttons on the control panel that the user can use to start and stop the dryer, choose the drying program, change the time and temperature, and so on. Like a human brain, the control board collects information from the temperature sensors, thermostats, and security motor relay and sends commands to the power board.
The power board is like a principal manager who sends commands to the working parts, mainly to the dryer’s motor and heating element.
The electronic control board with the control panel (user interface) can cause an issue when the dryer doesn’t stop, but it rarely comes. It happens only when the buttons are damaged, usually by moisture.
Remove the dryer’s top and the control panel and investigate the board for any trace of corrosion, loose or broken buttons or wires, and bad connections.
Power control board
This is the most common cause of the problem when you can’t stop the dryer. The power board is usually on the top left under the top cover of the Samsung dryer. It could also be in the control panel but is not connected to the user interface.
Look at the board’s components to understand why it caused our main problem. It works at 120V and always has several relays, which is why it is also called a relay board.
Why do we need the relays? The dryer’s drive motor uses 120V, and the heating element uses 220V. A dryer relay is a switch that connects/disconnects power on the motor and heating element. There are two components in the relay. The control circuit (coil) gets 12V on their terminals (from the user interface), and the load circuit provides 120V for the consumers. It doesn’t seem very easy, but it is not.
The user interface usually uses 12V. When you push the button START, you send a command (12V) to the control terminal on the motor and heater relays on the power board. These terminals are connected to the coil. When the coil is under electricity, it has magnetic energy that draws and closes the load circuit, and the dryer starts to drive and heat.
I recommend this video explaining how the relay works.
You can understand now that when the relay is faulty, the contacts of the load circuit could stay stuck, and the dryer will keep running even if you push the POWER or STOP button on the control panel.
This is why, in many cases, you can just hit the relays on the PCB and see that the problem is solved. Shaking the motor relay will unstick the contacts, and the dryer will work properly.
Watch my video below, showing this process.
Unfortunately, the problem usually comes back because the relay is already damaged. The PCB replacement is recommended.
Do we need to check more?
Remember the last thing: the dryer stops when you open the door. This is a security mechanism, and the door switch cuts the primary circuit for all the dryer’s components without using any other relays that could be damaged.
Here are some other tips: When the Samsung dryer doesn’t stop, check the heating element and security thermostat.
When the heater is shortened and its coil touches the metal frame, the dryer may run and heat uncontrollably. In this case, the security cut-off could also trip.
Honestly, there is one more option, which you can find on the net: The dryer doesn’t stop when you open its door. It could be that the door switch is damaged or stuck in the CLOSED position, so the dryer “thinks” that the door is closed.
However, in this case, the dryer properly dries clothes and stops while finishing the cycle. You can turn it off using the buttons. This is rare and more related to dryer safety.
Conclusion
If you suspect that the control board is indeed faulty, it may be wise to consult with a professional technician. They can provide a detailed diagnosis and ensure the repair is performed correctly.
Remember, while the control board is critical to the dryer’s functionality, it is essential to confirm that other components also function correctly before proceeding with a replacement.
The control board is one of the most expensive parts of the Samsung dryer, costing between $150 and $350.
