In the 80s we installed media pads on some 100 ton air-cooled chillers and some Trane "boxcars." They worked well in the dry climate that we were in at the time. It took work to keep them clean and the Celdek media only lasted about 4 years before it was completely calcified. There was virtually no water carryover, so the coils remained pristine. I would not suggest wet condensing coils because they will calcify rather quickly.

Our home is a 1979 - still has the original lightweight aluminum frame windows. We get away with a 3 ton unit for 2500 sq. ft. that will hold 73F at 105F. Being built on the side of a hill, the downstairs is half underground. We have an 8' overhanging deck on the southwest exposure upstairs. The indoor fan coil and all ductwork is within the conditioned space, with nothing in the attic. First house I've seen with rectangular steel ductwork throughout.

When we were looking to buy the house, I saw the 3 ton condensing unit and cringed because I knew darned well that it was way too small. Nope - it is undersized just enough to provide great dehumidification.

Hmmm, 3 tons on 1400 sq ft should be able to freeze you out of there! sounds like system is running really reduced capacity.

When was last time outside coil was cleaned?
Any chance you're running an 'inexpensive' pleated filter (the cheaper ones block inside air-flow, reducing capacity)

On hottest part of day, can you get actual temperature measurements of air coming out of the closest register, as well as temperature of air going into return?

If you only spray the coils while the unit is running, I suspect the fan will leave very little water on the coils to leave enough mineral buildup to impact the coils. As I noted earlier, my two old units were still running on the original condenser coils after 20 years when I finally replaced them.

It's the grass and leaf clippings from yard mowing that's their biggest culprit.

Outside coils are clean. I've done the measurements early afternoon with 58 out and 78 coming in.

Ducting could be mashed or have holes?

Don't know. No attic access. I'm pretty sure it's all metal ducting.

Ok - how old is system, and has inside coil ever been checked/cleaned?
something still seems off - could also be duct leak(s) - and when was system last checked (charge/performance)?

All that has been checked. Evaporator coil is clean. Charged was checked recently. System is 5 years old.

Only other thing I can think of would be inside fan speed set to low ? ;
system would do great at removing humidity,
(82 degrees at 30% humidity would prolly feel pretty good w/ceiling fans)
but would have lower overall capacity (what you seem to experience at hottest time of day).

Super hot temps outside do lower capacity a little bit (see mfgrs charts) - but still should easily keep up.

Manufacturers ( government?) fan speed setting was set at medium speed. I changed it to high setting. It does make a difference.

I just did some quick measurements of my windows to wall space on west side of house where all the hot afternoon sun is. We have roughly 102' of run on that side of the house. 42 percent of that wall space is windows. Each window is 8' tall. Every one of those windows get sun at the hottest part of the day and at the same time.

^^^^^^^^^^
Are your solar screens highest available darkness?

Yes, sir. And to the point I don't have a clear view.

That sounds like a greenhouse, not a house! Is that 320sq ft of west-facing windows?
You prolly need highest level solar screens AND highest level Reflective window-tint film applied to counter the (7 Tons?) of solar btu's hitting those windows!

Our electricity has only went out a couple times in 15 years, once during the summer. I put a 15,000 btu window unit in to have something to run with a generator if it happened again.
Last couple years i've started using it to help the main system when it is really hot. Set it a few degrees higher, direct vents so it moves air away from the main thermostat and towards
a hall in the center of the house where two big returns are.

Your windows are generating a lot of heat, may try a small window unit to help the main system during the day?

I don't know about the sq ft, but the home is long (think of a blimp with wings) and the windows run along the length of the wings from end to end. Not much depth to the house, so whatever room you're in, you have a window right there. Only 3 smaller windows are east facing.

We have a window unit in one of the rooms we stay in, but plan on getting another one for the main room where the thermostat is located and where most of the windows are.

RT, not trying to hijack your thread.

No problem. It’s all good info.

I really want to put in a mini split system upstairs. But don’t have the ballz to pull the trigger.

They have a filter I believe