Add a button on coolers that reverses direction.

[Zombull]

I know I'm not the only one who does it every now and then.

Build a cooler then wonder why your fridge is 100°F

Crap. Red arrow is pointing in. Shouldn't be an error that costs materials. Just let us reverse the cool/hot air flow.

[AileTheAlien]

+1
Given that Rimworld takes place in the far future, I can totally believe that coolers would be the fancy style of heat pump, which can run in both directions. :)