One Way Check Valve Check
WARNING: This page is about a different car, the 2001 Mazda Protege, 2001 Mazda Millenia, 2001 Mazda MX-5 Miata, 2001 Mazda MPV, and 2001 Mazda 626. However, it is still accessible from the selected car via links, so may be relevant.
Remove one way check valve. Blow into valve in direction of arrow on valve. Air should flow. Blow into valve in opposite direction of arrow. Air should not flow. If flow is not as specified, replace one way check valve.