VW: No Exterior Air / Water drip from dash


We’ve had a lot of rain lately. When I accelerate from a stop or make a turn I can hear water trickling inside the dash. There is also water running from under the dash onto the passenger side floor mat. Not a lot.

When my windows fog up driving in the rain, I turn on the defogger, but there is almost zero air coming out of windshield vent. In fact it only thickens the fog. I try to blow air through the floor vents and dash vents and there’s hardly any air at all either.

Herein I believe lies the rub: When I push the inside recirculation button, the air cranks at a normal level. So apparently there is something wrong with the exterior/outside air intake passage.

Could this also cause the water situation?

Any help, and I would be very happy.

1999 VW Jetta 2.0

Thanks much,


I think you have more than one problem.

First, the water noises: There is a drain for the AC evaporator, and if it’s clogged water will remain in the HVAC system instead of draining out onto the road as it should. I think your AC drain is clogged. The drain tube is on the firewall, low on the passenger side. Clean it with a flexible wire or blast of compressed air.

The other problem is more complicated. There are “flaps,” or “doors” within the ventilation system, which control the direction of airflow, the amount of “fresh” air vs. “recirculated” air, etc. If one or more of these flaps does not move correctly, air will not flow where you want it to. On most cars, these flaps are operated by vacuum, and if there is a leak in the vacuum system (loose connection, leaking vacuum hose, etc.), the HVAC system won’t work as it should.