This weekend I decided to check both of my AC units again to see if I could improve the performance. I removed the 6 screws and the plastic grate on both units. My filters were clean and the cold/return air baffles appeared to be in place for both units. But I went ahead and pulled the metal braces that are held up with the 4 long bolts that use a 1/2" socket to remove. Once I did that, I could see the entire baffle clearly. Even though the baffle has foam tape around it, it wasn't really making a good seal all the way around so some cold air had to be getting into the return air side. I used foil tape and taped all the way around each baffle on the top and both sides.
I also noticed there were some holes in the factory installed foil tape that went around the plenums that feed the round ceiling vents, and above those plenums there was no tape at all. That was allowing some of the cool air to just go into the ceiling void instead of into the plenums. So I taped all of that up real good too.
I re-installed the metal plates that are held up by the long bolts. There was not a good seal between the bottom of the baffle and the metal plate, so some cool air was getting into the return air side there. I was able to feed one piece of foil tape up between the metal braces and tape the bottom of the baffle on one side. So there is now no cold air getting into the return air side.
Before, with both AC's on, I was getting an almost imperceptible amount of air coming out of the ceiling registers. Now there is a very noticeable air flow out of them. I also pulled all of the ceiling registers off (what a pain to snap them back on), reached my hand in as far as I could into the plenum and discovered 2 of them were plugged up with the round piece of ceiling material that was hole sawed at the factory for the ceiling registers. That annoying fluttering sound is now gone and I'm getting good flow now from those 2 registers.
I also noticed than when just the front living room AC unit is running, I get some air flow from the bedroom ceiling registers and visa versa, so if I'm correct all of the ceiling registers are plumbed into one big plenum in the ceiling and the living room and bedroom ceiling vents do not function totally independently. This makes sense if I'm right so that both AC units support each other versus being dedicated to separate rooms.
That being the case, I will make a change in the way I operate the units. When its really hot during the day and I want maximum cooling in the living room, I will close the main vent coming out of the AC ceiling unit in the bedroom (both levers moved inwards towards each other), and close the ceiling register louvers in the bedroom so I get minimum cool air in the bedroom and keep the bedroom door open. With the bedroom thermostat turned all the way down to 65 degrees, it should keep pumping out maximum cold air into the living room area via the ceiling vents because it doesn't get cool enough in the bedroom to cut back on the cold air that unit generates. That should also direct maximum cold air flow into the living room area via the ceiling vents.
I'm now getting really good air flow out of all of the ceiling registers in both rooms compared to before. I leave the main vent in the living room AC unit open about 1/3 to supplement what comes out of the ceiling registers alone.
It was 100 degrees in Denver that afternoon and when I was done and had everything configured as described above, the living room cooled down quicker and cooler than ever before.
Now, this was probably already well known by most of you but I have a much better understanding of how both AC units function as one system now. Hopefully sharing my previous lack of knowledge will help someone else improve the performance of their AC system
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Randy & Dee
2018 DX3 37TS
"Orange Crush"
Took the filter out of the unit, cleaned it & the dripping immediately stopped. 
Linear Mode
