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FURNACE CONTROL BOARD
DIAGNOSTICS
FAULT SEQUENCE CODE — TROUBLE SHOOTING GUIDE
# of Blinks
Fault Condition
Fault Correction
Steady On
Control OK
1 Flash
Temperature limit switch is open
-Check Circulating Air Blower Inlet or Grill Outlet for Blockage, Inducer
Blower/Circulating Air Blower Run to Cool Heat Exchanger and Limit
-Check for Flame Roll Out Condition Causing Roll Out Limit Switch on
Burner Box to Open
-Clean Circulating Air Filter
2 Flashes
Pressure switch is open with inducer on
-Check Heat Exchanger and Flue System, Outlet and Inlet for Restriction
-Check Inducer Blower/Wheel for Operation/Airflow
-Check Pressure Switch
3 Flashes
Pressure switch is closed with inducer off
-Check Pressure Switch and Replace
4 Flashes
Lockout due to failed ignition
-Check for Broken Ignitor
-Check for Bent Ignitor Bracket - Ignitor too far from Burner
-Check for Flame Sensor Malfunction/or False Ground
-Check Gas Valve
-Reset Thermostat
5 flashes
L1/Neutral reversed or voltage not present
on L1
-Shut Off Power to Unit and Dis-Connect Cordset Plug from Wall Recep-
tacle.
Open Junction Box and Un-Reverse Polarity of Incoming Power Leads
Rapid Flash
Flame sense or internal control fault
-Check Ignitor Operation
-Check Flame Sensor for Malfunction or False Grounding
-Check Gas Valve
-Reset Thermostat
Note:
If the hot surface ignitor is to be replaced, be sure to disconnect all power to the unit. Be very careful in handling the new ignitor
as they are fragile and can be broken easily if hit or dropped.
ACF Greenhouses
