Microwave runs for a few seconds and then shuts off completely, sometimes resuming after cooling.

Safety first: Unplug the microwave before inspection.

Step-by-step checks:

• 1. Check ventilation: Ensure vents are clear and the unit has proper clearance. Clean any grease filters on over-the-range models.
• 2. Observe pattern: Note if the shutdown occurs only after long use or even on short cycles. Overheat issues usually correlate with longer runs.
• 3. Listen for fan: Confirm the cooling fan runs whenever the microwave is heating. If not, the fan motor or control may be faulty.
• 4. Technician checks: A technician can test thermal fuses/thermostats, inspect for loose connections, and evaluate transformer/magnetron temperatures under load.