Diagnostic/ Blank thermostat. I arrived and found that the thermostat was hot to the touch. I went up to the air handler and found the correct high voltage and low voltage. The fuse was also good. I then put a loaner T6 thermostat on the wall and the display came on. This meant that the old thermostat had gone bad. I picked up a new T6 thermostat and installed it. After testing system operations, the system is heating and cooling properly at this time.