Please throw any ideas my way. I don’t know what else to do. I live in a tropical climate. Temperatures reach 110 - 115 in the summer months. I’m basically a reptile and happiest when the house temperature is between 76 and 78 during the summer. I live in a condo with a vaulted ceiling. There is a big fan in the center of the living room that seems to circulate air fine, except for summer. The thermostat on the first floor is set for 78, when I’m at work, and it drops to 77 at 6 pm. I may set it for 76 degrees in the evening if I have guests over. My bedroom is on the second floor where the thermostat is set at 80 during the day, when I’m at work, and drops to 75 at 9 pm, so it will be cooler when I sleep. 

The problem: Condensation and mildew develops on the air vents on the second floor. I have to clean them constantly. I don’t know if it is because there is a sudden drop in the temperature from 80 to 75, or if it is because we live in a tropical climate (humidity inside reaches 70% some days), or maybe there’s not enough air circulating on the balcony. I do notice the air feels still and it’s hotter and more humid there (see pics). Each May I switch the center ceiling fan to turn counterclockwise to blow cool air down. I tried setting it to blow warm air down, but that heated up the first floor. The condo is well insulated, has low E windows, and blinds are closed during the day. I run a small dehumidifier in my room (humidity never drops below 60%, though). 

My question is: Could I solve this issue by adding fans on the balcony? If so, what kind of fans (ceiling, stand alone) and what direction should the air blow? I tried lowering the temperature on the second floor to 78 during the day, and it did nothing for the condensation issue. 

Need air circulation advice for air vents developing condensation when thermostat is set at 76 - 78 degrees F during scorching summers