[Former StClairSailor]

You have to be very careful with installing the PVC into the air ducts. If you run into a tight spot and push, you can easily tear into the duct and now the air runs into the area above the ceiling. I found my duct work in the A/C return had collapsed. I saw a flex hose which was wire wrapped heavy soft plastic. It won't collapse and will not damage the duct. You have to pull off the A/C return cover and go up top and remove the Air Conditioner, then run a wire from the return vent to the A/C area to guide it and push it through. Then screw or glue it down in the A/C area to hold position. While you have the A/C out take a look at the venting. I saw very poor taping in that area. I also saw quite a bit of sawdust. Did this on both A/Cs. The air movement was very much improved. I used a IR thermal gun to check the temp of the A/C return, 76 degrees. Then checked the output, 55 degrees. Similar reading were found from the front A/C. The outside temp was 91 degrees. The temp rose in the unit to 80 degrees. I then checked the walls. On the side the sun was not hitting, the wall was 81 degrees. On the sunny side wall the temp read in the 90s. Inside the rear cabinet above the window the temp was 101 degrees. So if the A/C is functioning properly now, what's the problem. Draw your own conclusions, but I believe I figured out the cause.