00 GMC Yukon Leaking water in Pass compartment HELP!

I have owned this car since new 00. I never had a problem w/water in th passenger compartment. The windsheild was replaced 6 yrs ago. It is not coming in the A/C drain tube. It is coming in the fresh air intake, through the blower. The part I dont understand I can stand there with a hose for an hour no leaks, but a light rain and my front carpet is soaked. I cannot take it anymore. I have taken everything apart and I cannot find anything wrong. The car has 100,000mi and is like brand new. I cant get rid of it. Please help.