Responded to service call for 10+ year old natural gas furnace with intermittent operation issues. Customer reported thermostat losing power and inconsistent heating performance. Performed diagnostic inspection with system running; checked for active error codes and evaluated potential causes (thermostat malfunction or control board/low-voltage issues). No faults were detected during visit as system was operational. Instructed customer on monitoring furnace indicator light for fault codes should problem recur. Discussed equipment age relative to typical life expectancy and scheduled follow-up appointment for replacement system estimate per customer's request.
