BTU stands for British thermal unit. A single BTU is the amount of energy it takes to heat 1 pound of water by 1 degree Fahrenheit. With air conditioners, BTUs denote how much heat a unit can remove per hour. A higher number means more power.

Your AC gives you little clues that could help you decide whether to repair or replace it. Some signs that mean it could be time for an air conditioner replacement include: old age, frequent repairs and decreased performance. On the flip side, leaks, frozen coils and strange noises are often issues that can be repaired.