Water was leaking inside on passengers side, now

Hole in firewall rain leakin down and in. At least thats my prob. Some silicone should work

Pull the fan and blower out of the enclosure and make sure the drain is really open, i will bet it isn't and has leaves blocking it on the inside.

Your heater core is leaking, and when it does, it drains into the foot well passenger side. Best case would be a hose that is leaking, worst case is the core itself. Replacing the core is a big job.

The evaporator drain might be clogged. Get under the truck or open the hood and look for a rubber nipple coming out of the firewall on the passengers side. Try sticking something in this hole to release whatever might be stuck in there, usually leaves or sediment. Be careful, don't go crazy pocking something in there. The evaporator core might be near the drain hole, you don't want to poke a hole in it.

The resistors are located in the firewall just above the blower motor. they have a heavier gadge wire going to it. As for the water if it is not antifreeze then you have a leak in your cowl area by the lower windshield. I ran in to this problem on several gm cars such as yours it can be deficult to find good luck

Sounds like your drain is pluged. The drain is on pass. Side on fire wall. More than likely will have to get under car to find it. Try shooting some compressed air into drain port

Make sure your cooling fans are coming on when the temp heats up. Are you talking about a leak inside the car or outside? Inside is usaully a drain tube for the A/C stopped up. Outside, look for a water pump or intake gasket.

it seems like u have either a bad switch or bad blower motor.

here's a link for view & instructions on troubleshoot & where resistor is.
http://www.autozone.com/shopping/repairGuide.htm?pageId=0900c15280217dd0

yea on bottom rt of ur windshield is what is called the cowl black plastic piece arond the bottom of ur windshield underthat should be weather stripping that may have come off