1974 Duster water leak

worked at a body shop in 70s, place air compressor hose in car with it open ,close car door and seal as good as possible, take dish washing liquid make up a 5 gallon bucket of soapy water, sponge it around windshield if it coming out you will see bubbles, if not at wipers , soap fresh air vents at cowl panel, you can see bubbles where ever water is getting in.