wet floor on passenger side only when it rains it is not coming from windshield on 2000 Nissan Maxima

only when it rains

Asked by for the 2000 Nissan Maxima
Has a custom radio system been installed, sometime the firewall plastic plugs are pull out, allowing water to get in, something to check.
No we've owned the car Sense new it's not coming from the ac checked the drain not clod