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Troubleshooting an Electronic Ignition Furnace

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Troubleshooting a Hot Surface Ignition (HSI) System
Flame Sensor Being Cleaned with Emery Cloth

Flame Sensor Being Cleaned with Emery Cloth


Troubleshooting and Repair
Furnaces with electronic ignition systems may be much more efficient than their early counterparts, but they do it largely through electronics. However, there are still some troubleshooting you can do but fixing the problems can involve replacement of parts more so than repair or adjustment.

PROBLEM: Furnace burner will not ignite

Possible Solution

  • With a Hot Surface Ignition (HSI) system, if a gas hissing sound is heard for about 7-10 seconds and the burners do not ignite, the furnace will go into lockout mode.
  • To reset turn the furnace power switch off and back on and try again. The switch is probably located on the side of the furnace. A reset button may also be found on the solid state controller. If resetting fails again, proceed as follows.
  • Turn off power and gas to the furnace
  • Remove and check hot surface igniter being careful not to touch the heat element. If it is cracked or damaged, replace the igniter.
      PROBLEM: Furnace comes on for 7-10 seconds then turns off

      Possible Solution:

      • Turn off power and gas to the furnace
      • Remove flame sensor from its bracket. Lightly clean the surface with fine emery cloth and replace.
      • The problem may also lie in a bad ground or the the black and white wires being reversed (reversed polarity) at the junction box or outlet powering the furnace.
      • The electronic ignition control module must ensure current flow through the flame sensor to ground and if the polarity is reversed in the circuit there is no voltage potential and the flame sensor does not work and closes the gas valve.
      • If the black and white wires are connected correctly and the flame still drops out, then the issue may be a bad ground. Using a volt-ohm meter, measure between the white wire and the ground wire to be sure you have no voltage.
      • If this does not work, replace the flame sensor. See Replacing an Electronic Flame Sensor.

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