Thanks to everyone that responded to my prior thread.
To clarify: the staging problem with my Infinity control ONLY occurs in cooling mode. Runs in high most of the time in the spring and summer. It is hot here.. Location: New Orleans,LA. Cooling degree days 2000+. Seems to run in high all of the time when temperature is greater than 85 degrees. Average humidity here is 80%+. ACDJR wire disconnected to allow infinity control to control staging as directed in the install manual. High cool latch set to 95 degrees. I can tell it is in high from the stat and the circuit board on the condensing unit. Dealer is clueless. Carrier tech support clueless. Paid an energy auditor to survey the house--test, run manual J, blower door test. She was clueless too as to why the unit ran in high all the time. Our utility bills were HIGHER than when we had 8 SEER unit. This unit is 16.5 SEER, 2 stage 38TDB w/ txv valve. Coils were clean (both), filter changed, superheat, refrigerant charge correct. Temperature differential across evaporator coil 20 degrees in high stage and about 12-14 in low stage. Perhaps Casper the friendly ghost has possessed our unit or gremlins. Perhaps I have a black hole that opens and lets warm air in while I am not looking? Nobody knows.
I want to just ignore this problem but I paid a fortune for this system and I want it to work correctly.
Strangely, the infinity control works flawlessly and seamlessly in heating mode. Starts in low fire, runs for ten minutes then goes to high fire, if needed. High fire only necessary when coming out of night setback or if it is below about 35-37 degrees. Low fire can mantain 68 degrees unless it is below about 36 degrees then high fire kicks in for brief periods.
If I had a single stage stat, as one helpful person suggested, then the furnace circuit board would do the staging based on "stored history of past cycles". Professionals on this site have the consensus that this is a poor staging and temp control. Although, I have no doubt that it may work for some systems, as someone reported.
A more pressing problem now though. It is soooo dry in here. Humidity is 19%!! target humidity=45%, humidifier on. I have a bypass humidifier installed for those 14 days or so that we need humidity added (like today) Outdoor humidity is 46%. Humidifier is correctly installed, working perfectly: open bypass, correct stat settings, adjusted low stage airflow, solenoid switch works flawlessly, water flows and drains, turns on and off manually in the "checkout" mode with advanced service mode. Stat says the humidifier is on and it is. Just not adding humidity. Outdoor temp is 40 degrees presently (daytime) upper 20's at night and windy 14mpg gusting to 22 mph.
Thanks all and help with this if you can.