Climate Conrol - Airflow Direction

I have a problem with the climate controls on my 97 Aurora.
I can't seem to direct the airflow to the floor.

When I set the knob to direct the heat to the floor, the flow stops
comming from the middle vents for a few seconds, and the returns (to the middle).


Has anyone had similar problems?

Thanks
Cold Feet in Canada

The ventilation flap mechanism is complex. It's controlled through a centralized vacuum control module with tubing running from it to each actuator. It sounds as if your floor control tube may have come off so the system defaults to the previous setting. Are all other settings functional? I'm not sure how much of the system is accessible without tearing apart the console/lower dash. You don't want to get into that. It will never be the same, ie.squeaks & rattles. Have the dealer do it. A good number of clips, screws, small plastic pieces will either be broken or lost in the process. Let it be their problem to replace all that stuff. Make sure they stick to their estimate, because they will try to pass it on to you.

All the other settings work normally, except the ones that send air to the floor.
I was testing it some last night, and ocasionally I could get air to the floor and it would stay, but if I changed to defrost (for example) and then back to the floor it would revert back to the middle vents.

Turning on defrost automatically turns on A/C, as long as A/C is on, the system won't allow air to floor only. Make sure A/C button is off. Does it make any diff in auto vs. manual mode? Or how high you set the temp?

I'm looking at a schematic for a 98 and it seems its all solid state Five of them, a/c mode actuator, drivers side actuator, heater/defroster actuator, passenger side actuator, air inlet actuator if I were guessing other that the head unit I'd check the heater/defrost actuator.

Solid state meaning servo motors at each position?

Yes 5 of them. And they say (behind dash on plenum ) ........must be a lot of plenum there !

Wow, those things are quiet. You can't hear anything when you change settings, which is part of the reason I thought it had to be vacuum. I must have been looking at the wrong thing under the dash.