Allied A97UH2E - Page 18

508433-01Issue 2345Page 18 of 70
Code Diagnostic Codes/Status of Equipment Action Required to Clear and Recover
E223 Low pressure switch failed open. Check pressure (inches w.c.) of low pressure switch closing on heat call.
Measure operating pressure (inches w.c.). Inspect vent and combustion
air inducer for correct operation and restriction. Resumes normal operation
after fault is cleared
E224 Low pressure switch failed closed. Check operation of low pressure switch to see if it is stuck closed on
heat call longer than 150 seconds. Measure operating pressure (inches
w.c.). Inspect vent and combustion air inducer for correct operation and
restriction. Resumes normal operation after fault is cleared.
E225 High pressure switch failed open. Check pressure (inches w.c.) of high pressure switch closing on heat call.
Measure operating pressure (inches w.c.). Inspect vent and combustion air
inducer for correct operation and restriction. Resumes normal operation
after fault is cleared.
E226 High pressure switch failed closed. Check operation of high pressure switch closing on heat call. Measure
operating pressure (inches w.c.). Inspect vent and combustion air inducer
for correct operation and restriction. Resumes normal operation after fault
is cleared.
E227 Low pressure switch open during trial for
ignition or run mode.
Check pressure (inches w.c.) of low pressure switch closing on heat call.
Measure operating pressure (inches w.c.). Inspect vent and combustion
air inducer for correct operation and restriction. Resumes normal operation
after fault is cleared.
E229 Ignition on High Fire - Information Only. Code is displayed if 1) low pressure switch fails to close, then furnace will
switch to high speed inducer to close both low and high pressure switches,
then furnace lights on high re, or 2) if continuous fan is active, furnace
lights on high re for 60 seconds to improve heat exchanger warm up time.
E240 Low ame current - Run mode. Check micro-amperes of ame sensor using control diagnostics or eld-
installed mode. Clean or replace sensor. Measure voltage of neutral to
ground to ensure good unit ground. Alert clears after current heat call has
been completed.
E241 Flame sensed out of sequence - Flame still
present.
Shut o󰀨 gas. Check for gas valve leak. Replace, if necessary. Alert clears
when fault is recovered.
E250 Limit switch circuit open. Check for proper ring rate on furnace. Ensure there is no blockage in
heater. Check for proper air ow. If limit not closed within 3 minutes, unit will
go into 1-hour soft lockout. Resumes normal operation after fault is cleared.
E270 Soft lockout - Exceeded maximum number of
retries. No ame current sensed.
Check for proper gas ow. Ensure that ignitor is lighting burner. Check
ame sensor current. Clears when heat call nishes successfully.
E271 Soft lockout - Exceeded maximum number of
retries. Last retry failed due to the pressure
switch opening.
Check pressure (inches w.c.) of low pressure switch closing on heat call.
Measure operating pressure (inches w.c.). Inspect vent and combustion air
inducer for correct operation and restriction. Clears when heat call nishes
successfully.
E272 Soft lockout - Exceeded maximum number
of recycles. Last recycle due to the pressure
switch opening.
Check operation of low pressure switch to see if it is stuck closed on
heat call. Check pressure (inches w.c.) of high pressure switch closing
on heat call. Measure operating pressure (inches w.c.). Inspect vent and
combustion air inducer for correct operation and restriction. Clears when
heat call nishes successfully.
E273 Soft lockout - Exceeded maximum number of
recycles. Last recycle due to ame failure.
Check micro-amperes of ame sensor using control diagnostics or eld-
installed mode. Clean or replace sensor. Measure voltage of neutral
to ground to ensure good unit ground. Clears when heat call nishes
successfully.
E274 Soft lockout - Exceeded maximum number of
recycles. Last recycle failed due to the limit
circuit opening or limit remained open longer
than 3 minutes.
Shut down system. 1-hour soft lockout. Check ring rate and air ow.
Check for blockage. Clears when heat call nishes successfully.
E275 Soft lockout - Flame sensed out of sequence.
Flame signal is gone.
Shut o󰀨 gas. Check for gas valve leak. 1-hour soft lockout. Clears when
ame has been proven stable.
E290 Ignitor circuit fault - Failed ignitor or triggering
circuitry.
Measure resistance of hot surface ignitor. Replace if open or not within
specications. 1-hour soft lockout. Clears when ame has been proven
stable.
Table 4. Integrated Diagnostic Codes / Status of Equipment