Responded to no-heat call for 3-year-old furnace that failed to operate after power outage. Diagnosed code 33 (faulty high limit) with voltage testing showing 28V across limit switch and infinite resistance when measured with ohmmeter. Found severely clogged and dirty filters contributing to overheating condition. Replaced high limit switch and restored normal operation.
Diagnosed non-operational furnace due to dead thermostat batteries. Replaced batteries and verified system operation. Furnace restarted successfully with thermostat now displaying proper temperature (44°). Advised customer about potential condensate trap freezing in high-efficiency unit and recommended maintaining home temperature above 55°.
Responded to no heat call for aging furnace that would either not heat above 60°F or would drastically overheat beyond setpoint. Diagnosed issue as dirty flame sensor causing improper system operation. Cleaned flame sensor, conducted system testing, and verified proper heating function restored.
Performed scheduled tune-up on 14-year-old furnace. System operational under current conditions. Noted potential deterioration and possible water damage in mechanical area requiring monitoring. Recommended continued regular maintenance to maintain system performance.
Completed routine furnace inspection on Lennox Merit Series system. Verified clean filter, good condition of flame sensor and ignitor, and solid electrical connections. Documented concerning condition of heat exchanger with photos, recommending annual monitoring. System burning safely at time of service.
Responded to service call regarding 18-year-old furnace in manufactured home producing loud buzzing noise. Diagnostic inspection revealed malfunctioning gas valve causing buzzing sound and blower motor with oil leakage. Performed complete system replacement including installation of new gas valve and blower motor to resolve noise issues and restore proper operation.
