Tech arrived to problem with downstairs thermostat. Customer stated that thermostat was blank and non operational. Verified thermostat had power behind display did visual inspection and verified nothing else was causing power to disappear. System is 21 years old and system is operational according to homeowner. Customer just wanted thermostat replacement. Tech replaced thermostat with standard 1H/1C thermostat and verified operations. Diagnostics were not performed beyond thermostat replacement. System is operational. No warranty on any repairs besides thermostat. Flood protection was noted. Thank you for letting TE CERTIFIED service your home.