1999 alero 3.4 lots or water into passenger side floor

Its either a bad connection on the blower motor resistor or a faulty blower motor resistor.These are known for over heating.

BLOWER MOTOR UNDER DASH ON PASSENGER SIDE.YOU HAVE TO REMOVE LOWER DASH PANEL UNDER THE GLOVE COMPARTMENT.FIRST TURN OFF RADIO.DISCONNECT NEGATIVE BATTERY.THIS WILL DISARM DASH AIR BAG AND BCM WHICH WILL PUT CAR IN THEFT MODE IF BUMP AGAINST WHILE REMOVING HEATER BLOWER MOTOR.WAIT 20 MINUTES BEFORE WORKING ON BLOWER MOTOR TO GIVE AIR BAG TIME TO DISCHARGED.

CHECK BLOWER MOTOR FUSE AND RELAY.IF ALL IS GOOD.BEST TO REMOVE BLOWER MOTOR HOTWIRE IT.IF DONT WORK REPLACE BLOWER MOTOR.IF BLOWER MOTOR WORKS.YOU HAVE FAULTY CONTROL SWITCH OR MODULE.BESURE TURN OFF RADIO FIRST YOU NEED TO REMOVE NEGATIVE BATTERY CABLE.WAIT 15 MINUTES BEFORE WORKING UNDER DASH.THIS WILL DISARM AIRBAG AND BCM UNDER DASH.YOUR BLOWER MOTOR UNDER DASH ON THE PASSENGER SIDE FAR TO BACK.YOU NEED TO REMOVE BOTTOM PANEL TO GET TO IT.

Are you replacing it because it has no speeds and doesnt seem to work? checked your fuses and tried replacing the blower motor resistor? I would try a blower motor resistor because it is the most common issue with most cars first. before doing the fan, if you are unsure locate your blower plug in and apply power and ground and if it comes on it is not the blower motor.

CHECK HVAC FUSE AND BLOWER MOTOR FUSE AND RELAY.IF ALL IS GOOD CHECK FOR POWER TO BLOWER MOTOR.YES BLOWER MOTOR DEFECTIVE.IF NO POWER GOING TO BLOWER MOTOR AND ALL FUSES AND RELAY GOOD.YOUR HVAC CONTROL SWITCH IS BAD OR YOU HAVE BROKE OR LOOSE WIRE AT CONTROL SWITCH.

With Air Conditioning

1. Disconnect the negative battery cable.
   
2. Remove the right side scuff plate.
   
3. Pull back the carpet from the passenger's side floor.
   

WARNING Be careful not to cut into the blower motor wiring!

1. Use a suitable utility knife to cut the wheel housing silencer in line with the blower motor wiring.
   
2. Detach the blower motor electrical connector.
   
3. For right-hand drive vehicles, remove the motor cover.
   
4. Unfasten the three blower motor retaining screws, then lower the blower motor assembly from the unit housing.
   

The blower motor assembly is located under the passenger's side dash panel



Blower motor mounting and location of the retaining screws and wiring-vehicles with A/C

To install:

1. Raise the blower motor into position in the unit housing and secure with the three retaining screws.
   
2. If removed, install the motor cover.
   
3. Attach the blower motor electrical connector.
   
4. Use tape to secure the silencer into position.
   
5. Reposition the passenger's side floor carpeting.
   
6. Install the right side scuff plate.
   
7. Connect the negative battery cable.
   

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

Noise from the blower says that armature bearings were going bad. Water on floor is a separate issue, likely the drain on the firewall is plugged. I believe your blower motor can be removed from the engine side of the firewall...it's on the passenger side.

Could be a fuse. If not it could be the blower motor or the resistor. First try hitting the blower motor passenger side underdash. Some times they stick. If this works replace the blower motor if not check for power at the blower motor if no power replace resistor if you have power replace the motor.

One suggestion. Have you checked the fuses ?

I would check the AC or blower fuse to start with. If you have the drivers manual it will show you where the fuse box is. Typically there are at least two boxes to check. One in the Engine compartment and one in the passenger cabin.

Look inside the lid of the fuse box to see which fuse may apply to the AC circuits or the blower and check to see if they are blow. the metal link between the two posts that plug in. If the link is missing you need to replace the fuse with one of the same rating. Make sure you know where you took the fuse out from and put it back in the same slot if its good. Check all the main fuses if possible to see if any have blown and replace if they have.