If the HVAC (heater) housing is not properly sealed at the bulkhead (firewall), water can leak into the passenger compartment. Foam sealant should be used to seal any gaps and the evaporator drain tube can be modified to prevent further water entry.
Car Problem Reports
Chrysler Town & Country Water Leak Due to HVAC Case Not Sealed at Bulkhead
Chrysler Town & Country Problem
Average Mileage: 75,000 mi (40,000 mi - 110,000 mi)
Visitor, 2003 Chrysler Town & Country, 110,000 mi
Water from air condintion leaking into front passenger floor.