It's the rainy season in Sacramento.

I was vacuuming the car on Sunday and noticed that the carpet under the passenger side floor mat was damp. The car had been in the garage for a week, but was driven in the rain before it was garaged.

It's not antifreeze, and the air conditioner has not been used in months (unless it comes on when the defrost is activated?)

The windshield gasket looks perfect and tight.

The car has a sunroof that someone sealed shut with silicone seal. Most likely, they had water dripping down their neck and didn't know that they needed to clear the drains from the sunroof, so they just sealed it up from the outside.

If the silicon seal job is failing and the sunroof drains are plugged, could water from up there find its way to the passenger floor without showing anywhere else?

Where else should I be looking?

Thanks guys.