During the hot summer months, a central air conditioning system can be a simple way to keep your home cool. By choosing an Energy Star-rated model, you know you're using the most energy-efficient model possible to save electricity and money. But if you have an older central air conditioner, swapping it out for a new one can be a very costly expense. Instead, one affordable way to tune up your older model is to install a modern, high-efficiency compressor. The compressor inside the air conditioning unit is designed to circulate the refrigerant into the hot air it pulls in. Older models work harder to cool the air, while newer models will do it more efficiently.