Air Conditioning Repair Certification (ETI) Practice Exam

A common symptom indicating a failing capacitor in an AC unit is that the compressor won’t start. The capacitor is critical for providing the necessary electrical boost to start the compressor, which is the main component responsible for circulating refrigerant throughout the system. If the capacitor is failing or has failed, it may not be able to generate the required starting torque needed for the compressor to run, resulting in the compressor being unresponsive when the system is activated.

While strange noises could indicate various issues within the unit, they do not specifically signal capacitor failure. Similarly, a clogged air filter can impact system efficiency but does not directly relate to the functionality of the capacitor. Lastly, if the system blows warm air, it could suggest numerous issues including inadequate refrigerant levels or problems with the compressor itself, rather than pointing to a capacitor issue specifically. Thus, the inability of the compressor to start is a direct and clear indication of a capacitor problem.