I just got a decent portable AC hooked up in the room because the temps are going a little over 90s on hot days. I have a pretty big fan that pushes pretty hot fresh air from outside my tarped room into it. My exhaust is also usually on 24/7. I left the AC on for a few hours today and it didn't seem to help. I'm thinking the fan bringing air in the room is just bringing in too much hot air for the AC to cool it down. Do you think it would be smart to turn the fan off during the day, or the exhaust? Maybe both?