*carlos, it could also be coming from the weatherstrip of the car doors, or even from the gap in between the window, then thru the door panels.

*the lark, typhoon is probably right, just reach under the dash from the front passenger side and make sure that the hose is directed outside the car.

may effect ba yun sa performance ng car?
cant see how. diba sa aircon pambahay may tumutulo ring tubig. yun din yon