Would you want to wear a fur coat in the summer? Probably not. Your cat probably isn't psyched about it either. It is best to leave the air conditioner on between 78–80 degrees for your feline while you are out of the house. This prevents your cat from overheating. The decision to use air conditioning does vary between each individual cat. Monitor the time yours spends around air vents when the AC is on to help judge how much your pet depends on the cold. It is also important to remember that long-haired, elderly, ill and obese cats need more cool air than others.