If you place a microwave in complete darkness, nothing significant will happen to the microwave itself. The microwave will continue to function normally as long as it is supplied with electricity and the control panel settings are adjusted correctly.
Microwaves do not rely on light to operate. They generate microwaves (electromagnetic radiation) to heat food, and this process does not require any ambient light. The microwave's internal components, such as the magnetron (the device that generates microwaves) and the electronic controls, will function just as they would in a well-lit environment.
The primary consideration when using a microwave is ensuring proper ventilation to prevent overheating. Microwaves generate heat during operation, and ventilation is essential to dissipate this heat. Placing a microwave in a dark or enclosed space without proper ventilation could lead to overheating and potentially cause the microwave to shut down to protect itself.
If you have a microwave installed in an enclosed cabinet or a built-in setup, it's essential to follow the manufacturer's guidelines and ensure proper ventilation to maintain safe and efficient operation. Always refer to the microwave's user manual for specific installation and safety instructions.