They are just AC units in reverse. The biggest effect humidity is going to have is on how much condensation is going to form on the exterior radiator. That’ll form frost that’ll have to be melted in a defrosting cycle. That’ll decrease performance and efficacy. Low humidity should keep that to a minimum.

If you want to see how weird it can get look at blightsight. Your consciousness can be blind but your body can still react to visual stimulus.

I think you mean RTFM. But in this case it’s WTFM so I can RTFM.