I had problems w/ climate control blower switching to the floor under accelleration. When the turbo kicks in, the intake is no longer under vacuum. I originally suspected the air check valves on the manifold, but they were fine.

I called a local volvo parts store/shop (not the local dealer) and they knew exactly what the problem was before I finished my sentence. I have heard others complaining about this here, at least twice.

The solution: (one of the few free repairs I have seen) If you take the panel below the glove box off, you will see a small "box" where all of the colored vacuum lines meet. Pull a bit of slack out of the yellow line and bend it shut (like you would w/ a water hose to stop the flow) and then put a nylon wire tie on it(fairly tight). By stopping the flow of air, the problem was solved. They reccomended cutting and plugging the line, but I was very skeptical, so I chose the least destructive approach.

I have not seen any loss of functionality. This is their alternative for replacing some very expensive climate control parts.

Hope this helps those struggling w/ this problem