Where to find Humidifiers - ARC Raiders The best places to find Humidifiers in ARC Raiders for your Expedition. Humidifiers are another important part to your Expedition Project in ARC Raiders. You will need to find five Humidifiers in order to progress past Stage 4 and into the final, pre-launch stage. As a blue, Uncommon item, these are slightly more difficult to find than the green and gray bits and pieces..Where to find HumidifiersHumidifiers are found in Residential locations in ARC Raiders. Stop by our ARC Raiders page for even more information on the game.