Poor cooling for new Puron AC unit or just the way some of them work?

A new (installed last year) ultra-high efficiency AC unit (Carrier 24ACB324A300) had cooling performance that seemed substandard. The thermostat temperature reading was 77F at the start, and the supply air temperature decreased from 75 degrees to 65 degrees in about 7 minutes, which seemed fine, but decreased very slowly after that, and never got below 62.6…

The refrigerant line was not very cold, and there was no noticeable condensation on it, either. The air being blown out of the unit was 73.3 degrees when outside air temperature was measured shortly thereafter at 71.8. The thermostat inside read 75F. These observations were after the unit had been run for over 90 minutes. This was early evening.

These observations certainly seem consistent with substandard performance, but I want to run it by some specialists to see if this might be the way some of these units run, or if there may be other considerations in play, such as duct configuration.

Ducts were properly configured to the extent I could observe, though the living room had a high ceiling, with my clients running the ceiling fan, and indeed was cooled more less effectively than the bedrooms. The thermostat was in the hallway in between. I measured the supply air temperature at the register in a bedroom nearest to the fan unit, which had strong flow.

In any case, running that long with so much less effect than I’m accustomed to observing does not seem energy efficient. Any insight would be much appreciated.

Most likely the unit was never properly charged to begin with. I find that periodically on new houses.