Heating, Ventilation, and Air Conditioning (HVAC ) Electrical Practice Test

What indicates that a contactor may need maintenance or replacement during operation?

1. It produces loud noise

2. Voltage supply is inconsistent

3. No measurable voltage at contacts

4. It shows overcurrent on the gauge

The correct answer is: No measurable voltage at contacts

A contactor showing no measurable voltage at its contacts is a significant indicator that it may require maintenance or replacement. This situation typically signifies that the contactor is unable to close properly, which can be due to issues such as burned or pitted contacts, mechanical failure, or an electrical fault within the contactor itself. When the contacts do not close, the circuit cannot complete, preventing power from being delivered to the load. This lack of measurable voltage at the contacts demonstrates a failure in the contactor's primary function, directly indicating a need for attention. In contrast, while the other indicators may suggest problems, they do not necessarily point to the immediate failure or required maintenance of the contactor itself. Loud noise could suggest faults but may be due to a variety of issues, voltage inconsistencies may arise from external power sources, and overcurrent readings indicate an issue with load rather than the contactor itself. Hence, the absence of voltage at the contacts represents a clear failure in the contactor's operation and highlights the need for maintenance or replacement.