What could cause short cycling in an HVAC system?

Short cycling in an HVAC system refers to the situation when the system turns on and off rapidly, failing to run through a complete heating or cooling cycle. This can lead to several operational issues, including increased energy consumption and wear on system components.

The correct answer identifies a range of causes that can contribute to short cycling. A faulty thermostat can misread the temperature, prompting the system to turn off too early or not operate at all when it's needed. An oversized unit can also result in short cycling because it cools or heats the space too quickly, failing to run for the required time to adequately condition the air. Refrigerant issues, such as low refrigerant levels or leaks, can lead to improper heat exchange, causing the system to cycle on and off frequently as it struggles to maintain the desired temperature.

While a faulty compressor might lead to performance issues, it is not the sole cause of short cycling, and low thermostat settings may not necessarily trigger this problem unless accompanied by other issues. Extreme outdoor temperatures can impact the unit’s operation, but they are not a direct cause of short cycling in the same way that the combination of thermostat, sizing, and refrigerant issues can. Understanding these elements is crucial for diagnosing and fixing short cycling effectively.