What is a ptac unit?
PTACs stand for: (packaged terminal air conditioner)
Where are they used?
In NYC most buildings and condos use PTAC units, for heating and cooling, they are located underneath a window.
How do i know if its time to replce it?
Most units manufactured before 2010 should have already been replaced, the average life span for the units is 5-10 years if you have them serviced once every two years.