Responded to service call for an 18-year-old Carrier furnace experiencing intermittent operation with error codes 12, 13, and 33. Diagnostic inspection revealed draft inducer motor with failing bearings causing squealing and scraping noises, oil leakage from blower motor, out-of-spec blower capacitor, and high limit switch activation despite low temperature readings (approximately 120°F). Heat exchanger inspection showed no cracks but significant temperature stress and rust formation. Reviewed replacement options with homeowner due to multiple component failures and age of system.
