[Former StClairSailor]

There are only 4 A/C air intake vents. Two for the rear A/C and two for the front A/C. They are oval shaped as stated. The round ones are air output vents. The intake vents have a tendency to collapse. This is why folks are adding the pvc piping. However, the pvc can tear the venting causing other issues. The alternative is to use 1 1/4" tubing with wire wound support. So if your A/C isn't performing well, chances are that the intake vents have collapsed.