I've got a 2000 Pontiac Grand Prix. I have a leak in my car. It seems to be coming from under the dashboard on the passanger side. If it rains hard, I end up with a lake in the passanger side floor board. Has anyone else had this problem.

It is a common problem. The water comes in via the HVAC air intake and drips down the firewall. Check out the passenger side intake cowling seals located by the wipers. Also, if you do not have a cabin air filter installed, installation of one will help maintain a better seal against water and debris. Finally, there is a drain hose in the HVAC assembly to help drain off water and condensation tht may be clogged.

You guys rock!!

I've experienced this as well and now I've got yet another answer, and to think I didn't even ask the question :-)

The HVAC drain tube is located on passenger side of the firewall and is a black rubber 90 degree boot.

It is a pain to get at on a 3.8L SC motor, but on the 3100 it's easy to get at. I had to remove the strut brace on my parent's Regal to then contort my arm and pull the plug. On my GP I just leaned over the fender and pulled the boot off.

If you have a two piece plastic intake cowl, then you're A) Lucky and B) Most likely have a filter in the blower intake. Either way, you should take off the intake cowl and look at the rubber seal That runs along the sheetmetal lip just below the windshield and just above the air intake for the HVAC blower. If that seals is loose, water will seep past it, drop straight down into the housing and get water everywhere.