Lennox G24M Error Codes

Equipment type not specified · Ducted Heating

• 2 FLASH SYSTEM LOCKOUT. FAILURE TO DETECT OR SUSTAIN FLAME.
• 2 Flashes Loss of Flame Sensed (More Than 3 Trials for Ignition)
• 3 FLASH PRESSURE SWITCH OPEN OR CLOSED.
• 3 Flashes Combustion Air Prove Switch Open
• 3 flashes Before combustion blower starts: pressure OPEN? NO: check main valve OFF; hold until…
• 4 FLASH HIGH LIMIT OR ROLLOUT SWITCH OPEN.
• 4 Flashes Primary or Secondary Limit Open
• 4 flashes Before ignition: Hi limit CLOSED? NO: check main valve OFF; hold until hi limit closes.…
• 5 FLASH FLAME SENSED AND GAS VALVE NOT ENERGIZED.
• 5 Flashes Flame Sensed Without Demand
• 5 flashes Flame OFF? NO branch: flame sensed with valve off. Lockout main valve OFF, combustion air…
• Alternating Fast Flash After15second prepurge and20second ignitor warm-up, sequential voltage above75volts /…
• FAST FLASH NORMAL OPERATION. CALL FOR HEAT.
• Fast Flash Loss of Flame Sensed Before End of 45 second Blower On Delay (3 or Fewer Trials for…
• Fast flash After combustion blower starts: pressure CLOSED? NO: check main valve OFF; hold until…
• Five Flashes Flame Sensed and Gas Valve Not Energized.
• Four Flashes Open Limit
• LED #1 & #2 Simultaneous Slow Flashes Thermostat demand satisfied: both lamps simultaneous slow flash. Combustion inducer…
• LED #1 ALTERNATING FAST FLASH / LED #2 ALTERNATING FAST FLASH Control self-check OKAY? NO branch: gas valve OFF, combustion air blower ON, indoor…
• LED #1 FAST FLASH / LED #2 FAST FLASH Thermostat calls for heat: LED1 FAST flash AND LED2 FAST flash.
• LED #1 FAST FLASH / LED #2 SLOW FLASH Polarity reversed? YES branch: LED1 FAST flash AND LED2 SLOW flash. No lamp synchrony…
• LED #1 OFF / LED #2 SLOW FLASH Initial pressure OPEN? NO branch: gas valve OFF, combustion air blower OFF, indoor blower…
• LED #1 OFF / LED #2 Slow Flash During operation pressure CLOSED? NO: gas valve de-energized, combustion inducer ON,…
• LED #1 ON / LED #2 ON Control self-check OKAY? NO branch: gas valve OFF, combustion air blower OFF, indoor…
• LED #1 ON / LED #2 SLOW FLASH Rollout CLOSED? NO: gas valve OFF, combustion air blower OFF, indoor blower OFF with…
• LED #1 ON / LED #2 Slow Flash Rollout CLOSED? NO: gas valve power OFF, combustion inducer power OFF, indoor blower OFF…
• LED #1 SLOW FLASH / LED #2 OFF Burner OFF? NO in continuous flame check: gas valve OFF, combustion air blower ON, indoor…
• LED #1 SLOW FLASH / LED #2 SLOW FLASH Burner OFF? YES: normal operation, LED1 SLOW flash AND LED2 SLOW flash.
• LED #1 Slow Flash / LED #2 Fast Flash Flame signal ABOVE0.7microamps? NO: low flame signal; does not affect control operation.…
• LED #1 Slow Flash / LED #2 ON Primary/secondary limit CLOSED? NO: gas valve de-energized, combustion inducer…
• LED #1: ALTERNATING FAST FLASH, LED #2: ALTERNATING FAST FLASH Improper main ground or line voltage below 75 volts; OR: Broken ignitor; OR: Open ignitor…
• LED #1: ALTERNATING SLOW FLASH, LED #2: ALTERNATING SLOW FLASH Watchguard - burners fail to ignite.
• LED #1: FAST FLASH, LED #2: SLOW FLASH Main power polarity reversed. Switch line and neutral.
• LED #1: OFF, LED #2: ON Circuit board failure or control wired incorrectly.
• LED #1: OFF, LED #2: SLOW FLASH Pressure switch open or has opened 5 times during a single call for heat; OR: Blocked…
• LED #1: ON, LED #2: OFF Circuit board failure or control wired incorrectly.
• LED #1: ON, LED #2: ON Circuit board failure or control wired incorrectly.
• LED #1: ON, LED #2: SLOW FLASH Rollout switch open. OR: 9 pin connector improperly attached.
• LED #1: SIMULTANEOUS FAST FLASH, LED #2: SIMULTANEOUS FAST FLASH Normal operation - signaled when heating demand initiated at thermostat.
• LED #1: SIMULTANEOUS SLOW FLASH, LED #2: SIMULTANEOUS SLOW FLASH Power - Normal operation Also signaled during cooling and continues fan.
• LED #1: SLOW FLASH, LED #2: FAST FLASH Low flame signal. Measures below .7 microAmps. Replace flame sense rod.
• LED #1: SLOW FLASH, LED #2: OFF Flame sensed without gas valve energized.
• LED #1: SLOW FLASH, LED #2: ON Primary or Secondary limit open. Units with board 63K8901 or 24L85: Limit must close…
• LED 1 Alt. Slow Flash / LED 2 Alt Slow Flash Ignition Watchguard. Four-second ignition trial: ignitor energized1second after valve…
• LED#1-Alternating Fast Flash, LED#2-Alternating Fast Flash 1.5 - On initial power-up the combustion air blower remains energgized. - DDiiagnosttiic…
• LED#1-Alternating Slow Flash, LED#2-Alternating Slow Flash 5.1 - Unit operates with a cooling and continuous fan demand. - Combustion air blower…
• LED#1-Fast Flash, LED#2-Slow Flash 1.3 - On initial power-up the comb. air blower does not energize. - Diagnostic lights…
• LED#1-Off, LED#2-Off 1.1 - Both diagnostic lights fail to light up. LED#1-Off LED#2-Off
• LED#1-Off, LED#2-Slow Flash 3.2 - Unit operates with a cooling and continuous fan demand. - Combustion air blower…
• LED#1-On, LED#2-Slow Flash 1.2 - Diagnostic lights flash the roll-out code. LED##11-OOn, LED##22-Slow Flash
• LED#1-Slow Flash, LED#2-Fast Flash 7.0 - Unit operates correctly but the diagnostic lights flash low flame sense code.…
• LED#1-Slow Flash, LED#2-On 3.1 - Unit operates with a cooling or continuous fan demand. - Combustion air blower will…
• LED#1-Slow Flash, LED#2-Slow Flash 1.4 - On initial power up the combustion air blower does not energize. - Diagnostic…
• SLOW FLASH NORMAL OPERATION. NO CALL FOR HEAT.
• STEADY ON CONTROL BOARD FAILURE.
• Slow Flash Normal Operation and No Call For Heat
• Slow flash Normal heating standby and thermostat-open end branch. At end combustion air blower stops…
• Steady On Control Failure
• Steady on Control self-check OKAY? NO branch. Control board failure. Lockout main valve OFF,…
• Three Flashes Pressure Switch Open
• Two Flashes Control Lockout

Reference only. Confirm against the manual for your exact model. Data release 105f66ecb9e96e5dc473025d.