I reported A/C problems here starting a few months ago, and after 6 months of hell I am happy to report that it is finally fixed!
A lot of folks provided input here, so I wanted to offer closure on this situation.
In summary, the issue was that I had a new 2.5 ton Trane 14xli R-410 system installed in March. Instead of a Trane Coil, they installed a Superior Coil/TXV. I did not know this intil 4 months later!
From the start, I had problems with the inside coils freezing, especially starting between 1:30pm and 2:30pm when the sun hit the back of the house. The air flow would reduce, the temperature would rise, and the furnace would sound like a big old steam-engine.
I had to turn the system off and leave the fan running for 30-45 minutes so it could recover, then turn it back on. It would run ok for a couple hours, then frost/freeze up again.
For every 2 deg in cooling I obtained, I'd loose 1 during the defrost period.
The installing contractors were out here no less than 7 or 8 times, with 4 different tech's working on it.
It never got fixed. My $200 Electric Bills sure showed that.
They replaced the inside coil/txv, recharged the system, put a freeze stat on (it turns out, a 26 deg stat, which of course is useless), and basically screwed with it for 5 months.
Their final verdict was the floor ducting in my 38 year old house was not capable of supporting the new A/C, and I would have to buy new ducting to install in the ceiling. Since it is a down-draft furnace, they would also have to build a box for the furnace to sit on, where they could tap off for the new ducting.
Well, considering this house has never had A/C problems like this, and since the estimate for this ductwork is like a month late, I decided to bring another contractor in for a second opinion.
I did, and I'm happy to report all issues have been resolved without ANY new ducting at all.
The second Superior Coil/TXV was bad. Well, it was either:
2. Damaged during the installation by brazing heat.
3. Totally wrong to begin with.
Item #3 is there because there are NO markings on the Coil for the tech to identify what it is. However, there are markings on the TXV and, get this, there are some indications that this is actually an R22 Coil/TXV they installed! We can't be sure however.
Anyway, I bit the bullet and told them to fix it. It cost me $1380 for the new coil, draw-down, installation, recharge, etc...
We installed a PROPER, matched Trane R410 coil designed for the 14xli and my XL80 furnace.
I now have more A/C than I could ever need.
Before, the temp split was 12 or 13 degree's (when it worked). Now the split is 15-20 degree's depending on when it's measured.
And it don't freeze any more
I can draw this house down to 65 degree's if I want, and it will do it quickly.
I could not get to 73 reliably with the system the way it was before.
The TXV failure on the old coil was kinda weird. It wasn't that it was opening too far, it was actually not opening enough. It was starving the Coil, and this was causing the freezing. When we put it into a cup of warm water you could hear the refrigerant flowing (never heard that before) and the split was correct, and the thing was actually blowing cold air again! With the TXV strapped in place, little refrigerant was flowing, and you could actually sit and watch the coil frost over slowly, mainly at the bottom.
I've gone from the worst air-conditioning I've ever had to the best air-conditioning I've ever had.
All it took was the right diagnosis and the right parts, and someone smart enough to figure it out.
Thanks for all your help here