Lennox ML193UH045P36B User Manual (English)

Questions and Answers:

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Gene HuntJul 31, 2025
What to do if Lennox ML193UH045P36B fails to fire in the heating mode, combustion air inducer does not energize?
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  Victoria BridgesJul 31, 2025
  If your Lennox furnace fails to fire and the combustion air inducer isn't energizing, check for correct wiring and secure connections to the combustion air inducer. Correct any wiring issues or replace loose connections. Also, verify that the pressure switch is open when the combustion air inducer is not operating; replace the switch if it's stuck closed.
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parkrobinAug 5, 2025
What to do if my Lennox ML193UH045P36B unit fails to operate in cooling, heating, or continuous fan mode?
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  Devin KnappAug 5, 2025
  If your Lennox furnace fails to operate, start by checking the 120V main voltage supply and address any power failures. Inspect the furnace wiring and connections, ensuring they are correctly wired to the power make-up box and transformer, and that the 24V wiring to the control is correct. Replace any blown fuses, and if they continue to blow, check for shorts. Verify that the door switch is activated when closed, check the wire connections, and test the switch's continuity; replace if defective. Confirm the transformer output is 24V, replacing it if faulty. If these steps don't resolve the issue, the control might be defective and require replacement.
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Stephanie HeathAug 10, 2025
Why Lennox ML193UH045P36B Furnace indoor blower fails to operate in cooling, heating, or continuous fan mode?
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  Marcus RobertsAug 10, 2025
  If the indoor blower in your Lennox furnace isn't working, first check the wiring and connections at the control and blower motor, correcting any miswiring or loose connections. Then, verify that 120V is supplied to the blower by individually energizing 'Y', 'G', and 'W' on the low voltage terminal strip. Remember that when 'W' is energized, the blower starts after a 45-second delay. If there's 120V to each motor tap but the blower remains inoperative, replace the motor. If there's no 120V when 'Y', 'G', or 'W' is energized, the control is likely defective and needs replacement. Finally, check and replace the run capacitor if it's defective.
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Donald WalkerAug 15, 2025
What to do if Lennox ML193UH045P36B burners light but unit shuts down prematurely?
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  penny45Aug 16, 2025
  If your Lennox furnace burners light but the unit shuts down too soon, check for a restricted intake or exhaust vent and remove any blockages. Ensure the correct concentric vent kit is installed. Also, inspect the condensate drain line for proper slope and any blockages, ensuring condensate flows freely during operation; repair or replace any improperly installed lines.
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Derrick MatthewsAug 20, 2025
What to do if Lennox ML193UH045P36B Furnace fails to fire in heating mode, combustion air blower energizes, ignitor is energized?
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  joneslindseyAug 20, 2025
  If your Lennox furnace isn't firing, but the combustion air blower and ignitor are working, check that gas is being supplied to the unit. Verify the line pressure at the gas valve, ensuring it doesn't exceed 13" WC for both natural and propane, and reads a minimum of 4.5" WC for natural and 11.0" WC for propane. Inspect the gas valve wiring and connections at multi-pin control amp plugs or the valve for correctness and tightness. If 24V is supplied to the gas valve approximately 35 seconds after heat demand but the valve doesn't open, replace the valve. If 24V is not supplied, replace the control.