© 2022 Staheli West
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Faults
Fault 20: Low Fire SW Off / Purge Hold T18 Low Fire Switch (See Fault 223)
Indicates that the louver is not closing during the purge cycle or that the signal from the
low fire switch is
not reaching the Honeywell Burner Controller.
Causes
Troubleshooting
Fixes
• Faulty louver actuator.
• Test in “Manual Mode” to see
if louver actuator moves. Go to
Menu > Operations >
Manual
Mode. In Manual Mode verify
that internal louver actuator
switches are working by
observing relay ABD-1 and ABD-2
cycle on/off when the louver is
open/closed respectively.
• If a spare louver actuator is
available, swap it to see if it
works.
• Replace louver actuator (check
other causes before buying a new
component).
• Temporary fix: Reset louver
actuator by unplugging louver
actuator and then plug it back in.
• Faulty wiring path from louver
actuator switches to ABD-1 or
ABD-2.
• Obstructed path of the louver
actuator.
• Remove actuator and manually
move the louver to feel if there is
any resistance or obstructions.
• Remove obstructions.
• Blown fuse (F1) or (F9) in Panel
3.
2015 machines: F1 or F11.
2016 machines: F1 or F11.
• Visually inspect the fuses.
• Replace fuse.
• Blown fuse (F8) in Panel 2.
• Visually inspect the fuse.
• Replace fuse.
• Faulty relay ABD-2 (Panel 2).
• Swap with relay ABD-1 to see if
it works.
• Replace relay.
• PLC and touch screen not
version 3.1 or higher
(Version 2.3 or higher for 2015-
2016 machines).
• Check which version is being
used by going to Menu >
Information > Version.
• Update to Version 3.1 or higher
on the PLC and Touch Screen
(Version 2.3 or higher for 2015-
2016 machines).
• Faulty wiring.
• Inspect wiring for continuity,
voltage, and ground.
• Replace/Repair faulty wiring.
