Troubleshooting and Repair
Furnaces with electronic ignition systems may be much more efficient than their early counterparts, but they do it largely through electronics. And that to some degree, limits what you can do to repair or troubleshoot these furnaces.
For example, although a high efficiency condensing furnace may have a self diagnostic integrated circuit ignition control, you still need the proper equipment and training for diagnostic fault code storage and retrieval. 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 ignitor being careful not to touch the heat element. If it is cracked or damaged, replace the ignitor.
- If the ignitor is OK, the problem can be the control board or pressure switch. Testing these requires an experienced service technician.
Possible Solution:
- Turn off power and gas to the furnace
- Remove flame sensor from it's bracket. Lightly clean the surface with fine emery cloth and replace.
- If this does not work, replace with new flame sensor.
