Dogs with double coats are actually quite efficient at keeping themselves relatively cool because of the double coat.
Our old malamute used to dig herself a hole in the shady area of the backyard and hang out there for most of the day.
Our husky has no interest in hanging outside in the heat of the day. He spends most of his time in the house with the A/C snoozing on the kitchen floor. Occasionally he’ll switch to the bathroom. It’s the tile 
How do I know if my dog has a double coat? Dammit Sally is a mutt…probably a chow/shepard/biteybreed dog, as far as I can tell. She has a thick, shiny coat, and she’s black as her evil little stony heart. Would she be happier with a trim? (Not that she suffers, she also spends most of her time lounging on the AC vents and stealing all the other dogs’ food.)
Our springer spaniels have always gone to the groomer once a year, in the spring, for their summer clips. Neatens them up, keeps them cool, and helps keep ticks from hiding in the fur. We call them “hound dogs” when they’re freshly clipped.
Trimming their hair may be better than shaving with a razor. I can’t imagine they’d stay still enough to use the razor without accidentally cutting them.
Nobody means razor blades and shaving cream. People are talking about things like these. Of course you can get blades that well pretty much remove all the hair, like for showy poodle cuts.