The moonroof drain tubes are clogged.
Hello. This problem is common to Hummer H3s. It is an involved fix, and most of the incidences are related to the front drain tubes, as the vehicle sits at a slight rake to the front. Access to these is a complicated and a delicate situation involving removal of the plastic trim pieces on the area in front of the moon roof. You can then see the tubes, which are plastic, and go through a rubber grommet in the metal panel. You can use stiff plastic weed eater cable to work through the tubes and clear them out. The same goes for the rear, but it is much more work. I would recommend having a qualified specialist inspect your moonroof for you, to avoid a lot of frustration and possible damage to the interior of your Hummer.
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