What is the most expensive part of an hvac system?

One of the most expensive parts of your air conditioning unit is the compressor. As the central element of your system, the compressor is responsible for circulating refrigerant through the system, which is responsible for cooling the air in your home. The cost of a new HVAC system is much less important than making sure what you buy is right for your home. And no matter what you pay, the system itself is actually secondary to the company that recommends, installs and maintains it.