Good afternoon! Just a bit of input from the UK!
www.canineconcepts.co.uk make a fan that attaches to your crate. It runs either on batteries, or you can buy various different adapters seperately.
What's good about it is, you can buy optional cooling cartridge
freezer packs that slot into the fan and blow the very cold air around.
It comes under Deluxe thermostatic dog crate fan - and there's a $ conversion bit at the top of the page....
Sally + Harry x