They also made a crapton of noise. The hotels often didn’t change the filter, so you’d instantly get a stuffy nose when you walked in. They were always right under the curtain, so it would recirculate the air caught in the curtain and cycle off and on too much because the air temp fluctuated too much.

I spend a lot of time in hotels. It was always a mixed bag with these. If you got a good one it was almost an exception rather than the rule.