Ac Won't Turn Off At Set Temp. Testing of the sensor will require the technical specifications of the thermistor for your model and a multi-meter. That scenario will work in just that way dependent upon your air conditioning system working properly.
I lowered it to 71 same thing happened- it went down to 71 and remained on. Air from unit does not feel cold enough. Or if your thermostat has a HEAT OFF COOL or FAN AUTO OFF control set the control to OFF or COOL.
Set to 77 reads 78 not on.
It instead relies on the supplemental heating system that is usually an electric resistance heater. Inspect the control board for any signs of a loose connection to the sensor as well. Most HW thermostats actually read in tenths of a degree but display whole numbers. Dirty condenser coils Another cause of this could be the condenser coils.