If running continuously, let the thermostat sit for 30 min. to allow the temperature to stabilize.
If the fan icon is on with no fan, or if the icon is off but the fan is running.
Verify that the G wire in the thermostat is connected properly
Verify copper wires are not exposed & touching other wires
Verify heating/cooling power switch is on.
Verify the circuit breaker isn’t tripped.
Verify furnace door is closed securely