There’s no such thing as a “non-vital” part of your central air conditioning system. All parts need to work well for the system to operate effectively and efficiently. But if any part were to be awarded the title “The Most Important AC Component,” it would be the compressor. It’s the literal heart of the air conditioner because it is what causes the refrigerant to circulate through the system. The compressor changes the refrigerant to a high-pressure hot gas that allows for the heat exchange process to start. Without a working compressor, an air conditioning system will function as nothing more than a large fan blowing around room temperature air.
The compressor usually lasts for the full life of the AC. In fact, it’s often a dead compressor that signals the end of the air conditioner’s lifecycle (around 10 to 15 years). However, a compressor might fail early—and usually it’s not worth the cost to fix it.