Perhaps because of their narrow doors, with a second door into the vestibule, the V-sets cope with the heat well, unless the air conditioning goes out in a carriage, in which case it tends to empty out as soon as there is space in the other carriages.
The Tangara windows are tinted, so they don't let in much heat, and they have stronger air conditioning. It gets hotter in the platform level sections, which have metro type seating and standing room, but is OK in the seated upper and lower decks.
The M-bugs have even stronger air conditioning, and AFAIR, there are two independent air conditioners in each carriage, so their air conditioning cannot fail all at once.
None of them are kept as cold as the trains I remember in Singapore, but that is probably driven largely by choice of thermostat setting. I've been accused of being a Marxist, yet while Harpo's my favourite, it's Groucho I'm always quoting. Odd, that.
