2009 Toyota Corolla Owners Manual - Page 307

4-3. Do-it-yourself maintenance n Replacement method Remove the air conditioning filter and replace it with a new one. The "↑UP" marks shown on the filter should be pointing up. n Checking interval Inspect and replace the air conditioning filter according to the maintenance schedule. In dusty areas or areas with heavy traffic flow, early replacement may be required. (For scheduled maintenance information, please refer to the "Scheduled Maintenance Guide" or "Owner's Manual Supplement".) n If air flow from the vents decreases dramatically The filter may be clogged. Check the filter and replace if necessary. NOTICE n When using the air conditioning system Make sure that a filter is always installed. Using the air conditioning system without a filter may cause damage to the system. 342