where is the location of the cabin air filter on 03 sienna?

Hello, Dave here, contributing to RepairPal and providing expert advice since 2010. This vehicle does not appear to be equipped with a cabin air filter. When you say "service your AC" - what do you mean? Does your air conditioning system function properly by dehumidifying the interior and defogging the windshield as well as blowing cold air when desired? If it is working as it should, there is no "servicing" required. If it is not working properly, then a properly certified technician able to work with refrigerants to perform needed testing. https://repairpal.com/auto-repair-near-me Click the link or call us at 877-913-1554. We'll gladly find you a certified RepairPal shop in your area.