How to get rid of CO₂ in a house with A/C in hot summer?
You want an high-efficiency heat exchanger.

https://en.wikipedia.org/wiki/Heat_recovery_ventilation

Basically, you pipe in fresh air, but have it cooled before, while you heat out the air that is going out. It's typically installed on central hvac systems.

It needs maintenance to be efficient and it is quite often overlooked by contractors as it's hard to notice when it's not working.