Microwave stops mid-cycle and displays E3; may beep repeatedly and refuse to restart until cooled.

Safety first: Unplug the microwave before removing any panels. Internal components can be hot immediately after use.

Initial checks:

• Allow cooling: Let the microwave sit unplugged for 30–45 minutes. Try running a short cycle. If it works briefly then shows E3 again, overheating is likely.
• Inspect vents: Check the rear, sides, and underside (over-the-range models) for blocked vents or grease buildup. Clean with a soft brush and vacuum.
• Verify installation clearance: Ensure the microwave has the clearances specified in the Magic Chef manual; cramped cabinets can cause chronic overheating.

Internal inspection:

• Remove the outer cabinet. Locate the magnetron thermostat/thermal cutout (small round or rectangular device clipped to the magnetron or waveguide area).
• Check for signs of discoloration or melting around the thermostat and wiring.
• Use a multimeter to test the thermostat for continuity at room temperature. Most magnetron thermostats should read closed (continuity). If open at room temperature and not resettable, it is faulty.
• Spin the internal cooling fan by hand; it should move freely without grinding. If seized or loose, replace the fan motor.

Corrective actions:

• Replace a failed magnetron thermostat/thermal cutout with the exact Magic Chef-specified part.
• Clean all vents and filters (for over-the-range models, clean or replace the grease filters and charcoal filter).
• Replace the internal cooling fan motor if it does not run during cooking.
• If the magnetron shows signs of overheating (cracks, burnt smell, discoloration), replace the magnetron as well.

When to call a pro: If E3 persists after thermostat and fan replacement, the control board may be misreading temperature or driving the fan incorrectly and should be evaluated by a technician.