2006 yukon ac drain tube

Depends on where the water is coming from. The 2 most often causes of water buildup is either the heater core is leaking or the AC condensate drain tube is blocked. If the heater core was leaking, you'd smell antifreeze or see steam coming from the vents while driving. The AC condensate drain tube lets condensation water to drip overboard from the housing. This tube is on the bottom of the AC case on the firewall side under the hood. Sometimes you need only pinch it to open it to drain out the water buildup..

Condensation Drainage tube could be clogged.

That is not anything to be concerned about, it is just water from the AC core condensation, the blower fan air pressure forces it out the tube when you start it. What would be a problem is if the drain was clogged..

Bulletin No.: 03-01-39-011B
Date: November 22, 2005
TECHNICAL
Subject:
Water Leaks Into Passenger Compartment Through HVAC Module Condensate Drain Tube When Parked on Incline/Uphill Position (Install Auxiliary Drain Tube Extension)
Models:
2003-2006 Saturn ION Sedans and Coupes
Supercede:
This bulletin is being revised to include the 2005 and 2006 model years. Please discard Corporate Bulletin Number 03-01-39-011A (Section 01 - HVAC).
Condition
When vehicle is parked on an incline with the front end up during a rainstorm or when driving uphill during a rainstorm, water may leak into the passenger compartment through the condensate drain tube opening of the HVAC module.
Cause
Water may drain out of the cowl drain, then drain down the front of the dash panel in the engine compartment and seep into the HVAC module condensate drain tube opening. The water then collects in the heater core cover and upon acceleration may leak into the passenger compartment through the heater core cover seams.
Correction 1. Open the hood and locate the HVAC module condensate drain tube in the engine compartment on the right side of the dash panel.
Important: During installation of the auxiliary drain tube, do not make contact with the HVAC module foam gasket located at the base of the HVAC module condensate drain tube. If the auxiliary drain tube is pushed on too far and makes contact with the foam gasket, water may leak into the passenger compartment.
2. Slide the auxiliary drain tube onto the HVAC module condensate drain tube and make sure that the auxiliary drain tube is angled downwards after installation.

Most probably your condensate drain is blocked. Check to see if the usual dripping at the left front tire is continuing or not (after running the A/C and the vehicle is stopped). If not you have a choked drain pipe. The drain hose is located to the left of the engine compartment just below the AC lines coming out of the firewall. There is a rubber tube about 1" diameter and it has a small plastic tube 3/8" coming out from the bottom side of the larger tube. Please take care accessing the tube as there are pipes and tubes really hot in the vicinity. It is always a good idea to wait till the engine has cooled down. The drain tube sometimes gets blocked and causes leaking onto the rug area inside the truck, just pull the small tube out by pulling it down and clean the small/large tube. If there is any water from the AC it will drain out.

That sounds like the AC condensation drain tube/hose is plugged up.

The AC evaporator/core condensation drain tube is located on the passenger side of the fire-wall towards the bottom of the fire-wall, (it resembles a heater hose that is coming off from the fire-wall and it connects to nothing, and it is just to drain the AC condensation) and it is easily viewed from under the vehicle. Use long pipe cleaners folded in half to clean out the AC drain, and be very careful that the AC evaporator/core, or the heater core is not damaged from using any hard or sharp objects to clean out the AC drain.

The drain tube from the evaporator housing is most likely plugged up. With the vehicle in the air locate the drain tube on the passenger side of the firewall and using coat hanging or something similar carefully snake it through it Be careful as a lot of water may pour out and don't go crazy poking with the coat hanging as the evaporator core is at the other end of the tube.

The vehicle has drain holes or tubes that allow the condensation on the evaporator coil to drain. If these are blocked by debris then the water will raise to a level capable of leaking into the vehicle.

if you look on the engine side of the firewall you will see a rubber tube on the passenger side of the vehicle bent at a 90 degree angle that is the drain tube. very carefully try to insert something stiff into tube to see if it is blocked