As Murphy’s law dictates, my portable A/C unit suddenly died while in operation on the hottest day of the summer.
No smoke, no explosion, just suddenly turned off and was then completely dead. No lights, no beeps, nothing.

Before the room got too hot, this needed to be solved. Let’s take panels off and take a closer look:

The power supply was was quickly identified as the culprit, because the logic board wasn’t being supplied with 12V.
I then checked all semiconductors on the power supply only to find that this schottky diode was a dead short in both directions. Oops!

After a quick diode swap, the PSU started up normally and everything was back in order:

(and yes, I’m aware of the issues with single hose A/C units…)