If you don't charge an AC properly, the consequences can be significant. The most common problem is that the AC will not cool the car as it should. This can lead to overheating and, in extreme cases, engine damage. It can also cause premature wear on other components such as the compressor, condenser, and evaporator. In addition, if the AC is not charged properly, it will use more energy and put stress on the electrical system of your car.