when i open the slideing sun roof i get a " pulsing " noise kind like a helicopter sound at almost any speed.. it is almost painfull to my ear drums? it is almost like the cabin of the tahoe is preasurizing and de-preasurizing. its a 2001 tahoe its a factory sun roof. any ideas..

 

crack open another window...

 

Check the vent caps at the rear of the truck. If you have aftermarket vents or the originals are clogged with debris, you will have cabin pressure issues at most speeds with windows open.

 

how do i check them and where at the rear?

 

See the black plastic grille things on the rear door pillars? Those are the cabin vents, they go through the pillar inside by the rear windows. I've seen people cover them up with chrome or silver covers and it plugs up the interior of the car.

Sometimes if the car is sealed really well the fresh air function of the HVAC will slow down at the vents with the windows closed vs the windows open.

Pressure Relief Valve Replacement (Utility)

Removal Procedure

1. Open the lift gate.
2. Remove the outer quarter panel upper applique.
3. Remove the upper rear garnish molding.
4. Remove the corner rear garnish molding.

1. Depress the locking tab on the back of the pressure relief valve to remove from the rear of the vehicle.
2. Remove the pressure relief valve from the vehicle.

 

sweet thanx

 

It is called buffeting. My Tahoe does it too with only the sunroof open (not when cracked) or only one of the rear windows is open. The air is also very turbulent with only the front windows down. Rolling down the rear windows relieves both the buffeting from the sunroof and reduces the front turbulence. I am also going to check the function of the rear vents to see of there may be a blockage there.

 

Something I forgot to mention is that there should be a popup spoiler on the sunroof. When you slide the glass back does a spoiler pop up at the front?