In the event of a power outage or power surge, the thermostats may reset and go back to address 1. Check the thermostat addresses by holding the mode and fan buttons simultaneously for twelve seconds, this will show the address of the thermostat. Multiple thermostats with the same address will cause the controller not be able to communicate with them. In this case, set the thermostats back to the correct addresses. If you do not find a solution to the issue in this FAQ section, contact support.