A microwave that operates but does not heat may have an internal electrical, switch, control or heating-system problem. Diagnostic testing is needed to determine the actual cause.

Sparking or arcing may be associated with metal inside the cooking cavity, food residue, damaged internal surfaces or electrical components. Stop using a microwave that repeatedly sparks until the cause has been identified.

Turntable problems can involve the motor, coupler, roller support or related components. Inspection helps determine whether the issue is mechanical or electrical.

The problem may involve the door latch, door switches, controls or related electrical components. Because the door-switch system is an important part of microwave operation, it should be properly diagnosed before repair.

Buzzing, humming, grinding, or rattling noises may be related to the turntable system, cooling fan, electrical components, or other internal parts. Diagnostic testing can help determine where the noise is coming from and what is causing it.

A microwave that shuts off during operation may have a problem with overheating, door switches, electronic controls, wiring, or another internal component. An inspection is needed to identify why the cooking cycle is being interrupted.

An unresponsive display, keypad, or control panel may be caused by a power issue, damaged keypad, wiring problem, electronic control board, or related component. Testing the control system can help identify the actual source of the failure.

The decision depends on the microwave’s age, type, condition, repair cost, and the component that has failed. After diagnosing the problem, a technician can explain the available repair options so you can decide whether repairing or replacing the appliance makes more sense.