26Step Possible Cause Check-out procedure Corrective actionElectronic air filter and Humidifier8 Condensing unitCheck for 24 volts betweenterminal Y and C on theelectronic fan control Yes - Compressor ONNo - Check thermostat and wiring9 Electronic air filter Check for 120 Volts onterminal ''EAC'' of theelectronic fan control(thermostat must call a Heat,Cool or Fan ON demandYes - Electronic filter failureNo - Change the electronic fan control10 HumidifierCheck for 120 Volts onterminal ''HUM'' of theelectronic fan control (burnermust be energized)Yes - Humidifier failureNo - Change the electronic fan control7.0 SERVICEWARNINGELECTRICAL SHOCK, FIRE OR EXPLOSION HAZARDFailure to follow safety warnings exactly could result in dangerousoperation, serious injury, death or property damage.Improper servicing could result in dangerous operation, seriousinjury, death or property damage.• Before servicing, disconnect all electrical power to furnace.• When servicing controls, label all wires prior to disconnecting.Reconnect wires correctly.• Verify proper operation after servicing.REGULAR MAINTENANCECheck complete operation at least once a year. In Canada see B139, (Maintenance), forrecommended servicing procedure. Clean flue pipes on a regular basis. Replace flue pipes ifthere is any sign of corrosion or other problems. Gaskets should be checked and may have tobe replaced.