water in the cabin Grand Prix
If you have a sun roof, the drain holes are probably plugged. If you have A/C, then it's probably the drain that is plugged. Find the drain tube and run a stiff piece of wire through it. That should clean out the debris.
If you're losing coolant too it could be a leaking heater core. Any fog on the windshield? If so I vote for the heater core. HTH. -Jim
Mine gets water inside if I park it facing up hill in rainy weather. I suspect it is coming in around a cowl vent somewhere, but since simply parking it level or facing downhill solves the problem I haven't bothered to look further. As for the possibility it is a heater core, simply determine if it is clear water or has coolant in it. If it doesn't taste, look, smell like antifreeze then your heater is not the culprit.
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