Clean it out!
“Make sure that carpeting, furniture or draperies are not blocking them. Putting furniture over registers, or in front of radiators blocks the amount of heat that register/radiator can emit into the room, thus causing your system to run longer cycles, and (you guessed it!) cost you more money to operate.”
https://www.howellsac.com/blog/top-10-energy-saving-tips-for-fall
