why not look here a central air conditioner's compressor stops with a hot day, the higher-stress limit switch might have tripped; you may be able to reset it by pushing the button, located in the compressor's access panel."On the heat pump, you can in fact attain what we call a coefficient of performance that is bigger than the heat energy that's inserted or maybe the energy that's inserted," Goss explained. "A basics COP of 1 usually means generally you put one kilowatt in and you receive one kilowatt out.