Great job! Definitely pretty unforgiving with the time limit on Warm (or maybe I'm just bad). Using one color for all the art and changing it as the heat rises is a really clever way of using the 4 color palette. It really makes the whole level feel like it's heating up too.
I will say I wish it was a little easier to tell what tiles were walls and what weren't (specifically in the sections that are kind of maze-y with a lot of 1-tile wide paths all right next to each-other, it gets kind of unclear what path leads where). Having some kind of pattern on the inside or edges of wall tiles I think would have really helped with this, even if it was simple.