Space is cold. And the Falcon's environmental controls, like everything else in the ship, have taken a beating over the decades. They're inbound towards Lexorus 2 when the environmentals crap out again and the temperature starts falling.
They've dealt with glitches before. They know what to do. Turn the auto-pilot on, while Han heads for the tool locker and Chewbacca climbs into the access well. Han hands down tools, occasionally takes components of the control circuitry, and reads the diagnostic screen while Chewie tries to figure out where the fault is this time, and how to juryrig a fix long enough to get to a supply depot before they freeze to death.
This one's bad, worse than usual, and takes longer to repair. Even Chewbacca is feeling the cold by the time he realizes that Han has stopped chattering. It takes longer than it should for Chewbacca to realize what's going on with his partner.
It seems like Han talks all the time, but Chewbacca knows there are many many topics that Han won't touch. (Chewbacca, on the other hand, doesn't talk much, but he doesn't mind talking about anything.) And although it has taken years, he's learned to hear at least some of the things that Han won't say.
Right now, what's Han's saying, without a word is: I can no longer feel my feet, and my fingers are too numb to grip that #10 hyper-spanner that you asked for. My teeth have stopped chattering, and I don't feel so good. Also (and this is the part that burned through Chewbacca's preoccupation with the circuitry): I'm scared. This might kill me, and I don't want to die this way.
Chewbacca climbs out of the well, feeling the frost crackle on his fur. He goes to the emergency locker and pulls out their one-time-use Emergency EVA suits, rips the tab to activate Han's, and bundles him into it. He activates a heat-stick and throws it in as well before doing up the closures. The emergency EVA's cost a small fortune, but they'll provide heat and pressurization and air for a full day. Chewie figures it's worth it, just for the heat, right now.
He brings his own suit to the edge of the well -- he'll climb into it soon if the problem drags on.
The problem does drag on, and he does climb into his suit, and once Han can talk again they ride down to Lexorus suited up.
Han complains bitterly about the cost of replacing the E-EVAs on top of the cost of the environmentals. But that's just chatter. He never says thank you, but Chewbacca hears it anyway, in the Wookiee delicacies that Han adds to their provisions list, and their new route that'll take them close enough to Kashyyyk for a trip home.