Microwave shows E3 and stops heating; fan may run briefly then shut off.

Critical safety: Unplug the microwave. Internal components can store lethal voltage. Do not touch the high-voltage capacitor, transformer, or magnetron terminals unless you are trained and have discharged the capacitor properly.

Steps to address E3 overheating:

• 1. Check external ventilation: Ensure the microwave has adequate clearance on sides, top, and rear as specified in the Galanz manual. Remove any obstructions from intake and exhaust vents.
• 2. Clean vents and filters: For over-the-range models, remove and clean the grease filters. Vacuum dust from rear and side vents.
• 3. Access internal cooling system: Remove the outer cabinet. Locate the cooling fan (usually near the magnetron and transformer) and the magnetron thermostat (thermal cutout) clipped to the magnetron or waveguide.
• 4. Test the cooling fan: Spin the fan blades by hand; they should move freely. Check for obstructions. Test the fan motor for continuity with a multimeter. Replace if open or seized.
• 5. Test the magnetron thermostat: With the unit unplugged and cool, disconnect the wires from the thermostat. Check for continuity. It should read closed (continuity) at room temperature. If open, replace the thermostat.
• 6. Inspect the magnetron: Look for burn marks, cracks, or melted insulation around the magnetron. If damaged or if overheating recurs after thermostat and fan replacement, the magnetron may need replacement by a professional.