I have a 95 Blazer which i thought was great...... until it rained. i am an aussie living in chile and it sure does get wet here. after sealing the windscreen, re-doing the door seals and generally going crazy i found my mobile pool still leaks when it rains (passenger side only). not coolant just good ol H2o. i have taken the cowl off under the windscreen but can see no pools of water or any drain holes to speak of. there must be some surely ...but where? can i access them from under the car. if any one can post a picture or can tell me where the hell they are you can have my first born

 

Have you tried getting in the vehicle and getting sombody to take water hose to it while you try to find what area its coming from. Maybe you could get a better idea where it might be coming from.

 

Read this thread. Post # 9 by D_Beezy 18. He is having the same issue on a 99.

 

Door hinge pins/bushings.

 

Ok. water is entering from a flap under the dash passenger side. fresh air? cant tell what it is and cant get to it easily. the water runs down the firewall and into the floorwell
thanks

 

Sounds like a vent stuck open. Take some duct tape and seal the grates where your front wipers are. Then hit it with some water and see what happens.