Nest Thermostat is stuck at 77 and when I set it at 75, it says 2 hours to reach that temperature

[Nandhinidj]

Got new carrier A/c for both upstairs and downstairs. Along with Neat thermostat about a year back. The thermostat had a mind of it own and get to get help figuring out in the beginning but after a year my downstairs stays so hot and when I check the thermostat it shows 77 as internal temperature and if I set it at 75, it says +2 hours and after 2 hours nothing changes. Very frustrating 

[CoolingWizard]

@Nandhinidj ,

Over the last year your Nest Learning Thermostat has been learning how well your HVAC works.  It compares the outdoor theme, the indoor temperature, the indoor humidity level, the outdoor humidity level each every time the system was activated.  If the system begins operating outside of the learned performance, it will report a need for a service call.  Since it has not done that, yet, we have to assume your system is not currently capable of cooling your downstairs area.  Having said this, you can check a couple of things. 1) Is your filter clean or does it needs to be replaced. 2) is the outdoor unit free from any vegetation or other items that might block or impede the airflow. 

AC Cooling Wizard