What could cause an HVAC system to short cycle?

Short cycling in an HVAC system occurs when the system turns on and off frequently without completing a full heating or cooling cycle. This can lead to reduced efficiency and increased wear and tear on the system.

A dirty air filter can restrict airflow, causing the system to overheat or fail to cool effectively, which may trigger the thermostat to turn the system off prematurely. Similarly, improper thermostat placement can result in inaccurate temperature readings, leading the thermostat to cycle on and off when the room temperature has not reached the desired set point. Both of these factors directly impact the HVAC system's ability to operate efficiently and maintain consistent indoor temperatures.

In contrast, while an overcharged refrigerant can affect system performance, it typically wouldn’t be a direct cause of short cycling such as the factors associated with airflow and thermostat placement. A malfunctioning reversing valve primarily pertains to heat pump systems and would more likely cause inefficiencies rather than short cycling, and excessive insulation could actually contribute to longer cycles by keeping the conditioned air from dissipating quickly. Thus, the combination of a dirty filter and poor thermostat placement aligns most closely with the causes of short cycling.