split ac no enough cooling?

the most common reason why your split and window AC is not cooling is because of unclean air filters. ... Dirt in the AC filters block the passage of cool and warm air inside the ducts. It could also make the evaporator coil freeze, thus blocking the passage of cool air from the outlet.

I had the same issue, got some good results with Canadian Duct Cleaning Company https://semsductcleaning.ca/ 

Try taking your coat off.

Get a manifold gauge and check the pressures, superheat and subcooling when the unit has been running for 15 minutes.  It will lead you to the cause.

actually it was bent copper pipe.,and my ac doesn't have expansion valve,,thanks everyone

what is the outdoor temperature?  if it is pushing up toward 50 degrees, there's almost no ac unit that will keep you cool.  {and I'd still look at the expansion valve and whether it is stuck or incompatible with the refrigerant}

May be it is the expansion valve on the A coil in the attic. Did you get a new unit in the attic?   It could be that if you have a real old expansion valve, it is not compatible with the current freon coolant, and does not cool very efficiently.  You will have to change out the expansion valve, and may be the A coil.

New outdoor unit with fresh recharge?

Why would a new unit need anything as far as charging it goes?

If all is running as you say it is definitely the refrigerate, wrong type, wrong, charge, wrong metering device possible.

What are the amps the compressor pulling? That might tell you something.