The answer to 'why is my air filter blowing hot air' is that the air filter may be clogged or blocked, preventing proper airflow through the HVAC system. This can cause the air to become heated as it passes through the restricted filter, resulting in warm air being blown out.
Some common causes of a clogged air filter include dust buildup, pet hair, and other debris. Over time, as the filter becomes more restricted, it forces the HVAC system to work harder, which can lead to higher energy bills and potential damage to the system components.