If the heater core were leaking, the film would be very difficult to remove and the defroster would not clear it.
The problem is moisture in the ductwork, most likely caused by a clogged or restricted evaporator drain.
Steve
98 Contour SE Sport 2.5 Duratec ATX The wifey's car
89 Taurus SHO - 246K miles
94 SHO ATX - 190K
1997 F-150 5.4L ATX - The Workhorse 150K.
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