Which of the following is a sign of system inefficiency in HVAC?

High energy bills and frequent cycling are clear indicators of system inefficiency within an HVAC system. When an HVAC unit is inefficient, it has to work harder to maintain the desired indoor temperature, leading to increased energy consumption. This is reflected in elevated energy bills. Additionally, the system may cycle on and off more frequently to try to reach and maintain the set temperature, causing further wear and tear on the equipment.

In contrast, signs such as consistent indoor temperatures suggest that the system is operating effectively, maintaining the desired climate without unnecessary fluctuations. Regularly scheduled maintenance typically ensures that the HVAC system is running optimally, preventing inefficiency from developing. Low humidity levels alone are not an indicator of inefficiency, as they can be a desired condition in certain climates.