OBH Nordica Stuck Relay or Shorted Control Circuit

Microwave interior light and fan run when the door is closed, even without pressing START.

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Safety Warning

This repair may involve working with high voltage components or water connections. Always unplug the appliance before removing any panels.

If you are not confident in your ability to perform this repair safely, we strongly recommend contacting a professional technician.

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Possible Causes

Welded relay contacts on control PCB, Shorted triac, Miswired door switch, Control board failure

How to Fix / Troubleshooting

Danger: A microwave that runs unexpectedly is hazardous. Unplug it immediately and do not use until repaired.

  • Step 1 – Confirm behavior: Verify that the fan and light (and possibly turntable) run as soon as the door is closed, without any program selected.
  • Step 2 – Inspect door switches: With power disconnected, check that the door switches are correctly wired and mounted. A miswired switch can cause unintended operation.
  • Step 3 – Control board inspection: Remove the control panel and inspect the PCB for burnt or discolored relays or components.
  • Step 4 – Replace control PCB: In most cases, a welded relay requires replacement of the entire control board with an OBH Nordica-compatible unit.
  • Step 5 – Safety test: After repair, verify that the microwave only runs when a program is selected and START is pressed.
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Repair Difficulty

Professional Required 5/5

Required Part

Main Control PCB
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