Newb a question. I am using the search function, but it is taking a while to go through those posts.

I have a Goodman 12 seer, 5 ton unit in a 2100 sq ft house with 9 ft. ceilings.

The house was built in 2000, so the unit is 8 years old. Being in Arizona, temps are in the 110's during the summer. For the last 7 summers, it has been fine. This year, the inside temp will not go below 80*. I can set the temp at 81, it will kick on at 82 - bring it down to 80 and kick off just fine. If I set it at 80, it will kick on at 81 and continually run because it won't go below 80.

I have tried a couple different thermostats, new filters and have had 3 different service companies out here to look at it. All 3 have said that the unit is working at maximum efficiency and there is nothing wrong with it.

There must be something different as the last 7 years was not an issue cooling the house to 77*.

Any thoughts??