Air vents not working right - 1998 Buick LeSabre

The exhaust inside the car would suggest the vents in question have fallen apart somewhere in the dash between the engine compartment and the interior allowing fumes to enter the cabin. Get that checked at a garage right away. Very dangerous to breath exhaust fumes.

What year is your Envoy ? Probably high speed relay .

Check under the dash to see if the duct work for the vents has come loose.

You may have to have the body computer "flashed" by a dealer scan tool. Sometimes the body computer looses data when the battery is disconnected. Sometimes it relearns itself after a few trips.

I would say the blend door actuator is not working right. It directs the flow in the vent system.

The A/C module placed inside central console has air flaps for air flows guiding against center, lateral, lower, defrost - air vents. Air flaps are acting by electrically motorized mechanisms. Here you must search for damages!

SOUNDS LIKE THE VENTS ARE PULLING AIR FROM OUTSIDE, YOU CONTROLS FOR THE VENTS ARE OFF SINQ. TRY TO MOVE THE CONTROL BACK AND FORTH WORK THEM HOT TO COLD AND DEFOAST TO HEAT TO AIR WORK ALL THOSE EVERY WAY YOU CAN ,MIGHT HAVE A STICKING VENT OR VALUE, THANKS HOPE THIS HELPS ,ROBERT

Damper/flap for driver's side is probably stuck. Try moving the selector from cold to hot several times. Also, move the recirc/outside air control if the previous doesn't work.

hello,good day,seems all the clarification request is all good,if all tips are done,but the problem is not corrected,send your car to a dealer,maybe one of the step motor of air flap is stuck or synchronized of all air flap is needed,they have the star diagnose to perform the job,or your recirculating pump need tobe check,ty

you have a servo motor that operates the blend air doors in your dash. this is probably the reason . you have to take it to a shop for them to replace it. disassembly of the dash without breaking it is difficult with out the right tools. please rate this solution thanks.