What is the compressor's job?

• A. To decrease pressure
• B. To cool the system
• C. To increase pressure
• D. To compress heat

Answer: (C)

The main idea is that the compressor's job is to raise the refrigerant’s pressure to drive the cycle. In a vapor-compression system, the compressor takes in low‑pressure vapor from the evaporator and compresses it into a high‑pressure, high‑temperature gas. This high‑pressure gas then moves to the condenser, where it releases heat and becomes a liquid. Only after that does it go through the expansion device and evaporator again to absorb heat.

So the compressor isn’t there to cool the system or to decrease pressure. It also isn’t correctly described as “compressing heat.” While compression does raise the gas’s temperature, the key function is to increase pressure to keep the refrigerant circulating and to enable heat rejection in the condenser.