water is getting in the cabin of my 1999 grand prix se, how hard is it to replace the water deflector and cabin air filter?

Asked by Nov 19, 2012 at 02:57 PM about the 1999 Pontiac Grand Prix 4 Dr SE Sedan

Question type: Maintenance & Repair

1999 Grand Prix SE has water on the floor of the passenger side and no one has been able to figure out why. Upon review of oil change records, a "cabin air filter" was installed about two years ago and i'm wondering if the water deflector was damaged.

6 Answers


Could also be the tube for the AC drain. The defrosters use the AC to dry the air coming out of the vents so the dry air can easily pick up the water molecules that form the fog on the inside of the windows.

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A common leak prone area is in the cowl at the base of the windshield. Sometimes it leaks around the cabin air intake. Sometimes the caulk dries out. Water runs down the fire wall behind the rug and pools in the footwell. Pull the carpet back, run a hose and see if that what's happening in your case. Another source is rust holes in the fire wall near the wheel wells so check that area while the carpet is pulled back.

1 of 1 people found this helpful.

Same thing happens to my 2003 if I park it facing uphill in the rain. The rest of the time it doesn't leak. I also know the sunroofs are prone to leaking. I'm not sure where the water leaks in from a leaky sunroof but its possible it runs down a window pillar and in along the firewall. The easiest fix for me has been not to park it facing uphill. Just a thought.


Evapotator drain hose for the ac. When the ac is on or defrost is on the evaporator accumulates moisture and has a hose that it drips from out of the car. When it cloggs the water will fill untill it spills out in the passenger floor board. Or are you sure its no5 coolant and you heater core isnt leaking?


Well you are all wrong. I have fixed many of these and the problem is a piece of weather stripping glued to a plastic piece that fits under the cowl. Remove the windshield wipers and screws that hold the plastic cowl down. Go to the passenger side and look in the area of the cold air intake. You will see the piece that I described earlier laying in the valley. The water is actually running down thru your blower motor to the inside of the car! Anyway look at the piece and you figure out how it reattaches. Use some weather strip adhesive to hold it in place and reassemble the cowl and windshield wipers.

11 of 11 people found this helpful.

6 month old question.....

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