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Flame sensed when no flame
should be present
Verify the gas valve is operating and shutting down properly.
Flame in burner assemble should extinguish promptly at the
end of the cycle. Check orifices and gas pressure.
Pressure switch stuck closed/
inducer error
Pressure switch stuck closed. Check switch function, verify
inducer is turning off.
1st-stage pressure switch stuck
open/inducer error
Check pressure switch function and tubing. Verify inducer is
turning on the pulling sufficient vacuum to engage switch.
Verify continuity through rollout switch circuit.
Open rollout/open fuse detect
Verify continuity through rollout switch circuit, check fuse.
1st-stage pressure switch cycle
lockout
If the first stage pressure switch cycles 5 times (open,
closed) during one call for heat from the thermostat the
control will lockout. Check pressure switch for fluttering,
inconsistent closure or poor vacuum pressure.
External lockout (retries)
Failure to sense flame is often caused by carbon deposits
on the flame sensor, a disconnected or shorted flame
sensor lead or a poorly grounded furnace. Carbon deposits
can be cleaned with emery cloth. Verify sensor is not
contacting the burner and is located in a good position to
sense flame. Check sensor lead for shorting and verify
furnace is grounded properly.
External lockout (ignition recycles
exceeded where flame is
established and then lost)
Check items for exceeded retries listed above and verify
valve is not dropping out allowing flame to be established
and then lost.
Grounding or Reversed polarity
Verify the control and furnace are properly grounded. Check
and reverse polarity (primary) if incorrect.
Module gas valve contacts
energized with no call for heat
Verify valve is not receiving voltage from a short. If a valve
wiring is correct and condition persists, replace module.
Limit switch open – possible blower
failure overheating limit
Possible blower failure, restricted air flow through appliance
or duct work. Verify continuity through limit switch circuit and
correct overheating cause.
Module Igniter contact failure
Fault code indicates the module igniter contacts are not
functioning properly. Replace module.
Module - internal fault condition
Module contacts for gas valve not operating or processor
fault. Reset control. If condition persists replace module.
Twinning error Check wire
connections.
If condition persists, replace module.
2nd-stage Pressure Switch Stuck
Open/Inducer Error
Check pressure switch function and tubing. Verify inducer is
turning on and pulling sufficient vacuum to engage switch.
Normal Operation with call for first
stage heat
Normal operation - first stage
Normal Operation with call for
second stage heat
Normal operation - first stage
Second stage call for heat on thermostat circuit with no call
for first stage. Verify dip switches are set for two stage
thermostat and check thermostat first stage circuit.
Configured for a multi-stage thermostat the Module will not
initiate heating unless first stage call from thermostat is
received.
Module will allow cooling to operate with only a "Y signal
from the thermostat but will also trigger this code. Verify
thermostat is energizing both "Y" and "G" on call for cool.
Check "G" terminal connections.
Low flame sense current is often caused by carbon deposits
on the flame sensor, a poorly grounded furnace or a
misaligned flame sense probe. Carbon deposits can be
cleaned with emery cloth. Check for improve furnace and
module ground. Verify sensor is located in or very near
flame as specified by the appliance manufacturer.
Normal operation. Waiting for call from thermostat or
receiving thermostat call for cool.
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