Has it been working alright throughout the rest of the season? I had an HVAC system that was incorrectly wired by the installers, so it actually ran the AC and heat pump at the same time, cancelling each other out. Might not be your situation but you never know!
That could be part of a problem if it isn’t circulating.
Make sure all the vents are open and not blocked by something inside. Switch filters if you haven’t recently, and make sure they are the right kind for your unit. If you can get to your duct work, see if it is leaking anywhere as that will reduce the pressure at the vents.
If you have ceiling fans, turn them on to help out. If you aren’t already, close curtains to block direct sunlight (east side in the morning, west in the evening).
I would recommend having a different company check it out since they won’t be defensive about the prior work.
You can’t “run the heat pump and a/c at the same time” because it’s a single unit. There’s a valve that slides when powered to switch the hot side with the cold side. That’s literally the only difference between a/c and a heat pump.
2.5 tons is right in the edge of being able to handle 1400 sq ft. Where do you live? It is two story or one? I think your AC might just not be about to keep up. Nothing wrong with it.
Could be a refrigerant leak. It will still run but won’t cool.
See if you can spot any ice on the lines on the inside and outside unit. Chances are the coils are frozen. You will need to let it defrost if this is the case. Could take up to 24 hours. Or less than an hour of you run the heat. Be prepared for water to leak from the inside unit as the drain may not keep up. Once fully thawed (you’ll never know when unless you can see inside an access panel, so longer is better) you can run it again. You should change the filter as low air flow can lead to frozen coils. If it happens again with a fresh filter, chances are it has low refrigerant and needs to be charged by an HVAC tech. If it’s low after one year, you probably have a leak somewhere. Hopefully it’s under warranty still.
