Sunroof Drain Hose Extensions

There may be a gurgle or sloshing sound heard on some 2021 Tahoe, Suburban, Yukon, and Escalade models equipped with a panoramic sunroof (RPO C3U). (Fig. 14) The sound may be coming from both front-right and front-left sunroof drain hose areas.


Fig. 14


The sound is usually present while driving the vehicle at approximately 50-70 mph (80-112 km/h) after a soaking rain or car wash. The sound may be more evident with the HVAC system off or with the HVAC system on and in the Recirculation mode setting.

If the sound is heard, check the condition of the sunroof front drain hose grommets where they exit in the plenum. The pressure in the plenum may potentially be too high to allow water to exit as designed.

It may be necessary to add drain hose extensions to both right and left side drain hoses. The extension hoses will attach to the existing sunroof front drain hose grommets (Fig. 15, #1) in the plenum behind the air inlet grille panel underhood and exit out of the plenum drain valves (Fig. 15, #2) on the side of the vehicle.


Fig. 15


The procedure includes installing PVC plastic tubing to the existing plenum grommet. Ensure the drain hose is installed perpendicular to the grommet. (Fig. 16, #1)


Fig. 16


Tie straps should be used to secure the extended drain hoses on each side of the vehicle. (Fig. 17)


Fig. 17


For the complete installation procedure, additional information and part numbers, refer to Bulletin #20-NA-219.


– Thanks to Hassan Abdallah

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