Room heating options

[Sam Faas]

Hi all,

I have a SFH in Phoenix and we replaced the window AC unit just last year in one of the rooms. The tenant is now complaining that it is too cold in that room. There is no central heating as an option.

I am loathe to rip out the existing unit to replace with a heat pump, are there any other options I can provide the tenant?  This is for smallish room.

Thank you!