Rain Leak

My 99 Voyager leaks rain in under the dash. Is there a drainage system up there for the cowl that might be plugged? It doesn’t seem to run into the car until I start driving.

Are You Sure It’s Rain Water? Water From The HVAC System Is Collected And Drained Out Utilizing A Tube That Passes Through The Firewall.

Plugging of the drain tube causes the symptoms you describe. Running air conditioning or defrosters can cause water to accumulate and spill when you start moving.
CSA

Three likely sources. The drain for the area under the vent in front of the windscreen is my first bet.

Second would be a clogged A/C drain. This would usually one be on the passenger side.

Third would be the sunroof if you have one.

Last a liking windscreen, door seal or rusted floor board.

If it is the drain, how do I unclog it? Is it easy to locate and get at?

Your Voyager Should Be Similar To My Caravan. Look For The AC Drain Low On The Firewall Toward The Passenger’s Side In The Engine Compartment.

Mine van’s drain is a short pipe stub with a black rubber cap over the end that is split to allow drainage. I guess the cap is supposed to keep things from entering from the outside, while allowing water to drain. It can trap bugs and leaves and stuff.

Pull the cap off and with a little hooked soft wire you should be able to pull stuff out of the end if there’s any there.

CSA