DIAGNOSIS: The thermostat is sending a call for HVAC, but the system isn't responding. This is typically a wiring or system power issue.
FIX: Go to Menu > Settings > Equipment > Test Equipment. Run the test for Cooling or Heating. Listen for a click from the thermostat and then at your indoor and outdoor units. No click indicates a wiring problem at the baseplate.
IF THAT DIDN'T WORK: The issue may be with the HVAC system itself, not the thermostat. Check your furnace/air handler door switch and the main system disconnect switch. A tripped float switch or blown fuse on the control board will also cause this.
HEADS UP: If the system runs during the equipment test but not during normal operation, check your schedule and temperature settings. An incorrect schedule or a hold temperature set too close to the room temperature can prevent activation.