As the temperatures rise, make sure you keep some windows open….just a bit. You see, a cooler will try to blow your house up like a big balloon and the air has to go somewhere! The best test of balance is to open your front door a crack with the cooler on and see if it slams shut, if it does, you need to open another window somewhere in the house to allow the air out. If you don’t do this, the humidified air will just build up, making the inside muggy, hot and uncomfortable. There is probably nothing wrong with your cooler, it just needs to breathe!
If you have air conditioning, this technique is not necessary, the air conditioner does not bring in outside air, it just recirculates the air in your unit.