What causes water accumulation in the Envision's cabin?
3 Answers
U-channel drain ports at both ends are blocked, or the drain pipe (for A/C condensate) at the lower outlet of the A/C evaporator drip pan is detached or clogged. Below are relevant details: Blocked drain ports: When the U-channel drain ports at both ends are blocked, water sprayed onto the windshield during car washing flows down into the U-channel. The air intake for the external circulation mode is located on the right side of the channel, and accumulated water in the channel submerges the intake, allowing water to enter the air ducts. Solutions: Open the U-channel cover plate, remove debris or sludge inside the channel, and clear the drain ports at both ends. From the exposed end of the condensate drain pipe under the car exterior, use an air pump to blow air inward to unclog the pipe. Check the connection between the interior condensate drain pipe and the A/C evaporator drip pan for detachment or signs of aging/cracking, and address as needed. The drain pipe (for A/C condensate) at the lower outlet of the A/C evaporator drip pan may be detached or clogged.
I've been driving a Buick Envision for over a decade, and recently encountered the issue of water accumulation in the footwell beneath the floor mats. Based on my experience, the primary cause is likely a clogged sunroof drainage tube—debris like leaves or dust can block it, preventing rainwater from draining properly and causing it to seep into the cabin. Another possibility is aged or cracked door seals, especially after car washes, which allow water to trickle inside. The air conditioning drain tube might also malfunction, causing condensed water to backflow onto the floor. For new cars, check if the door seals are intact. I recommend drying the accumulated water immediately to prevent mold and rust, then visiting a 4S shop to clear the tubes—or trying a compressed air blower yourself. Park away from trees to minimize debris entry.
My Envision has been accumulating water in the driver's compartment recently. As someone who enjoys figuring out car repairs, I decided to investigate myself. The water accumulation is likely due to clogged sunroof drainage holes, where rainwater or car wash water can't drain and ends up flowing inside. Another possibility is a faulty air conditioning drain pipe, where condensation water accumulates at the bottom of the evaporator and leaks out when the AC is used frequently in summer. Additionally, aging door seal strips allow water to seep in through gaps. I used tools to clear the pipes, cleaned dust from the door frames, and applied some adhesive to protect the seals. If the problem persists, I'll replace the entire seal strip or the AC drain valve. Regularly checking these areas can prevent trouble, and the hands-on process is quite fun, saving a lot on repair costs.
