What other component should be checked if the AC is blowing warm air?

When the AC system is blowing warm air, one of the most relevant components to check is the cabin air filter. The cabin air filter is responsible for filtering the air that enters the passenger compartment from the outside. If this filter becomes clogged with dirt, debris, or pollutants, it can restrict airflow into the cabin, leading to inadequate cooling from the air conditioning system.

When airflow is restricted, even if the AC system is functioning correctly in terms of refrigerant levels and compressor operation, passengers may still feel warm air because the system is not able to circulate sufficient cool air into the cabin. Therefore, ensuring that the cabin air filter is clean and unobstructed is essential for proper AC performance.

In contrast, while the engine oil level, transmission fluid, and brake pads are important vehicle maintenance checks, they do not directly impact the performance of the air conditioning system related to cooling the interior air. Thus, focusing on the cabin air filter is the most logical step when addressing issues with warm air coming from the AC.