I do recall not being able to actually get to the cockpit of a RAAF Caribou one day.
It had been locked up in the sun all day, and remember, they are painted dark green (matt), I opened one of the rear side doors, but could not make it to the front to get the overhead hatch open, to let out the heat, it was just much to hot, I couldn't believe it!
Had to turn back, could not make it, we finally opened the lower forward access to connect the battery (as I remember it!), and ran the rear ramp door open from the rear controls, and the other side door open, and just waited for about 20 minutes!
Inflight, they only have a heater system, not so different than my car system, as I remember it.
Luckily, we can fly it with both the cockpit side windows open, and the rear ramp door(s) some way open.
Them were the days!
Errrr..........1969, they were still new, then!