The answer to 'why is my air filter short cycling' is that the air filter is clogged and restricting airflow through the HVAC system. When the air filter gets too dirty, it can cause the system to short cycle, or turn on and off rapidly. This can lead to higher energy bills, uneven temperatures, and potential damage to the HVAC components.
Some common causes of a clogged air filter include pet dander, dust, and debris buildup. Symptoms of a short cycling air filter include the system turning on and off frequently, uneven cooling or heating, and higher than normal energy usage. The solution is to replace the air filter with a clean one, following the manufacturer's recommended replacement schedule.