Why is my microwave running but not heating?
Lights on, turntable turning, fan running, food cold. The microwave’s high-voltage side has failed: the magnetron that makes the microwaves, the high-voltage diode, the capacitor, or the transformer. A blown door-switch sequence can also cut power to the magnetron while everything else runs.
Usual fix: Magnetron, diode or capacitor, or a door switch. On a countertop model this often isn’t worth it; on an over-the-range or built-in it usually is.
- GE and Samsung over-the-range: the magnetron and diode are the common pair.
- Whirlpool and KitchenAid: door switches that fail out of sequence.