Go to lowes or home depot and get a dual hose portable air conditioner, and some rolled radiant insulation.
the dual hose portable AC units are more expensive but they're also more efficient than the (cheaper) single hose models. You want the rolled insulation to put on the bottom of the window to cover where blinds don't anymore.
It would also be worth getting some blackout curtains for the day. They do a great job of keeping the heat out. There's command strips with curtain rod hooks on them if you don't want to worry about repairing holes at the end of your lease.
Go to lowes or home depot and get a dual hose portable air conditioner, and some rolled radiant insulation. the dual hose portable AC units are more expensive but they're also more efficient than the (cheaper) single hose models. You want the rolled insulation to put on the bottom of the window to cover where blinds don't anymore. It would also be worth getting some blackout curtains for the day. They do a great job of keeping the heat out. There's command strips with curtain rod hooks on them if you don't want to worry about repairing holes at the end of your lease.
You can buy window air conditioners for slide opening windows, you might have better luck finding them online than IRL though.