Also check the AC drain. It is in the middle of the car, just behind the firewall. Lift up the cowl forward of the windshield and inspect the cabin filter.

The sun roof drains are a pain as the plastic tubing can come apart below the A pillar.

Removing the carpeting in the front is fairly easy, especially if you unbolt the front seats. The rear carpet is a pain as it also goes under the rear seat and is one piece from side to side.

My 1998 V70 had a leaking windshield seal, across the top. It only leaked during heavy rains, worse while driving at highway speed. I fixed that with a bead of silicone under the black plastic surround.
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Keeping it running is better than buying new