So it's been previously established that when your AC diverts to the floor vents under acceleration or at all times, your ducts have a leak somewhere.

My question is, where is a common place to start looking for leaks? Most of the vent system seems to be made of plastic under the dash, and I saw no leaks. Anywhere else I should look before I pull apart the blower fan housing?

So it's been previously established that when your AC diverts to the floor vents under acceleration or at all times, your ducts have a leak somewhere.

My question is, where is a common place to start looking for leaks? Most of the vent system seems to be made of plastic under the dash, and I saw no leaks. Anywhere else I should look before I pull apart the blower fan housing?

There are probably two devices that control the air flow to dash, floor, windshield, etc. One of the vacuum lines going to these devices has a crack. The vacuum lines terminate at the back of the a/c controls on dash.
(This is purely conjecture on my part.) Check shop manual or Alldata. Many garages will print a diagram out for you. Cost is about a a box of donuts. Dealer might even do that for you. Parts dept or service. Don't forget donuts.