What is the first step in troubleshooting an A/C that is not cooling?

The first step in troubleshooting an A/C that is not cooling is to check the thermostat settings. The thermostat is the control center for your air conditioning system, and incorrect settings can prevent the system from operating as intended. Ensuring that the thermostat is set to "cool" and that the temperature setting is lower than the current room temperature is essential before delving into more technical issues. If the thermostat is set correctly but the system still does not cool, it indicates that there may be other underlying problems that need to be addressed.

Other actions, such as replacing the air filter, inspecting ductwork for leaks, or examining the compressor, may be necessary in the troubleshooting process, but those steps generally follow the initial verification of the thermostat settings. Addressing the simplest potential issue first helps to rule out minor oversights before moving on to more complex components of the air conditioning system.