Microwave stops heating shortly after start and displays E3; fan may continue running.

Safety first: Unplug the microwave. The high-voltage section is dangerous. Do not attempt to remove or test the magnetron or capacitor unless you are a qualified technician.

• Step 1 – Check airflow: Verify that the rear and side vents are not obstructed by cabinets, walls, or objects. Ensure the intake and exhaust grills are clean and free of grease and dust.
• Step 2 – Clean vents and filters: If your OBH Nordica model has a removable air filter, take it out and clean or replace it according to the manual. Use a soft brush or vacuum to clean external grills.
• Step 3 – Listen for cooling fan: Start a short heating cycle with a cup of water. Listen for the internal cooling fan. If you do not hear it running while the magnetron should be on, the fan motor may be defective.
• Step 4 – Inspect magnetron thermostat: With the cover removed and power disconnected, locate the thermostat mounted on or near the magnetron body. Check for loose connectors or signs of overheating. Reseat connectors.
• Step 5 – Replace faulty thermostat or fan: If the thermostat is open-circuit at room temperature (and is specified to be normally closed), replace it. If the fan motor does not spin freely by hand or does not receive power during operation, it should be replaced by a professional.
• Warning: Persistent E3 errors after cleaning vents and replacing the thermostat may indicate a failing magnetron or control board. This should be handled by an authorized OBH Nordica technician.