Oldsmobile/Buick Repair: 2000 Buick LeSabre AC vent problem, auto body shop, vacuum tank

Question
Recently I was in a fender bender requiring replacement of AC condenser and radiator. Techs at auto body shop recharged the AC. After charging they ran the AC for at least 5 minutes. I test drove the car and realized that only the right two vents blew cold air.The 2 left vents blew warm air. I told the shop owner who then had his AC guy check the car. They found nothing. He and I drove the car around for a couple of miles and the left two vents slowly began to blow cold and continued to do so after we stopped back at the shop. Every thing seemed fine. I signed for the car and while driving home a small bump in the road seemed to be the event that caused the two left blowers to begin blowing warm again! That condition never existed before the fender bender. On the way home I hit a bump in the road and the left 2 vents began blowing warm air while the right two blew cold. I do not have individual temp controls in my car. The auto body shop is baffled. What do you think the problem could be?
Thank You.

Answer
Did they have to replace any vacuum lines near the radiator or ANYWHERE. There is a vacuum tank located up under the vehicle in back of the bumper just infront of the wheel well. It is very hard to see as you have to literally lie on your back and look up into a small opening in this area. If this vacuum tank is cracked or one of the hoses is punctured or pinched due to the accident or upon replacement of the front end parts this will cause a loss of vacuum to the interior components of the vehicle.

This would be my first suspicion as to look for pinched vacuum lines on the engine.

If you do not find anything there then you may have what is called a MODE DOOR ACTUATOR failure under the dash.

I wish I had a 2000 buick book so I could send you some pictures of hwhere to look, But I don't.

Look all around the engine compartment for vacuum lines that do not appear to look right.



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