Extending a mobile AC unit’s exhaust duct with an air extractor
June 4th, 2021—
Portable air conditioners are amazing, especially as we head into the hot summer months. But one big downside is having to place them close to a window that will fit the guard, otherwise it’s really tough getting the hot exhaust air out of the room. This is exactly the problem Hackaday user vincentmakes ran into when he set up a mobile AC unit, as his window was the wrong shape. To solve it, he created a little system that allows the AC unit to be plugged in on one side and then match its air flow to shoot hot air out of the window.
It measures the current draw of the air conditioner by using a Hall effect sensor and then correlating the resulting value with a target air speed. When the AC is off, the extractor cuts power to its fan, but otherwise will try to adjust the fan speed while the AC is on. Vincent designed a custom PCB for the project around an Arduino Nano Every for control and interfacing with the Hall sensor and a pair of relays. After some fine-tuning of the fan curves, the air extractor worked great for extending the reach of the AC’s exhaust, thus letting it escape outside.