For several years, I have had an issue where I just couldn't get enough heat when it was really cold at altitude, especially at night. More recently, I have started to get lower pressurization numbers until I turned the heat up a bit.
Aero Air looked into it, and found the recirculation duct to be full of holes. This is one of those flexible, wire wrapped with fabric sort of large hoses, and after 40+ years, mine was crispy-- and where it made some turns, it was all full of holes.
Once we replaced that-- huge difference! Pressurization works better, and cabin stays much warmer. I would guess it probably cools better as well, but since I have freon air that is less noticeable.