It goes without saying that the HVAC system in your home or business is complex. Of course, you don’t need to know all the details about how it functions to enjoy the benefits of properly cooled or heated air. But many of our customers enjoy learning a little bit about the different components of the system and their functions.

They find the information interesting and like that gaining some insight makes them a more well-informed consumer of HVAC services. With that in mind, this blog addresses a specific type of component in your air conditioning system: Compressor safety switches.

What’s the Purpose of a Compressor Safety Switch?

Compressor safety switches are also called pressure switches. Seeing “safety” and “pressure” in the previous sentence gives you a clue about their purpose.

As refrigerant travels through the refrigeration cycle, pressures and temperatures vary drastically at different points. For every point, there are normal, safe pressures and temperatures. Checking them is a way to measure and evaluate the charge or condition of your system.

For instance, on the low end of the temperature/pressure spectrum—the so-called “suction line,” where refrigerant has captured heat at the indoor coil and brought it back to the compressor—you’ll find the low-side pressure tap, usually with a low-pressure safety switch.

This switch monitors the refrigerant pressure coming back to the compressor. If it drops too low (for example, due to a frozen coil resulting from a low system charge or lack of airflow that causes the system to capture too much heat at once), the switch disengages the compressor to ensure the system doesn’t bring liquid (rather than gas) refrigerant back to the compressor and damage it.

On the other side of the compressor (the discharge line), you’ll typically find a high-pressure safety switch. Picture a scenario where the outdoor coil is plugged with material from a cottonwood tree (a common occurrence in some…