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FAULT CODES
Fault Codes
DIAGNOSTICS AND FAULT CODES
All furnace controls come standard with a 7-segment diag-
nostic display. During standby mode with no fault codes
present, the display will read “0” (zero). During normal
thermostat heating, cooling or continuous fan operation, a
letter will be displayed to describe the mode of operation
as follows:
C = Cooling or Heat-Pump Heat Operation
F = Continuous Fan Operation
H = Gas Heating Operation
When the control senses a fault present, it will display a
code to help in diagnoses and troubleshooting. A list of
normal operating codes and potential fault codes follows:
The method for displaying a two-digit fault is to display the
first (most significant) digit for one second immediately fol-
lowed by the second digit – which is also displayed for a
duration of one second. A ½ second pause is then dis-
played. Cycle repeats until the fault is cleared. Each
fault is flashed (displayed) a minimum of two times even if
the fault condition has cleared before the fault can be dis-
played twice.
DUAL FAULTS DISPLAYED
In some cases when two faults are present simultaneously,
both faults are displayed. These exceptions for dual faults
are noted below.
Sequence of display:
A. The first two-digit fault will be displayed once as de-
scribed above.
B. The upper-most horizontal segment of the seven-seg-
ment display is energized for ½ second
C. The second two-digit fault is displayed once as de-
scribed above.
D. The upper-most horizontal segment of the seven-seg-
ment display is energized for ½ again.
This cycle repeats until one fault is gone (in which case the
remaining fault will be displayed as described above) or
both faults are gone or otherwise as noted below:
1. When a failed ignition has occurred four times in a row,
the control enters one-hour lockout and fault codes
“10”
and
“11”
will be displayed alternately as de-
scribed above.
2. When flame is lost five times in a row, the control en-
ters one-hour lockout and fault codes
“10”
and
“13”
will be displayed alternately as described above (A-D).
3. While the control is in one-hour lockout due to an unex-
pected flame, the fault codes
“14”
(unexpected flame)
and
“10”
(soft lockout) will be displayed alternately at
the seven-segment display as described above (A-D).
4. While the control has entered a one-hour lockout after
declaring a dead blower after the main limit control has
been open for more than 150 seconds, the fault codes
“61”
(Non-operational blower) and
“10”
(soft lockout)
will be displayed alternately as described above (A-D).
Note: the dead blower fault and associated one-hour
lockout will occur up to four times in one heat call.
Upon declaring this fault for the fourth time in one heat
call, the control will enter hard lockout.
5. When the main limit has been open during a gas heat
call for more than 150 seconds and has not yet re-
closed, the fault codes
“61”
(Non-operational blower)
and
“22”
(open limit) will be displayed alternately as
described above (A-D) until the limit re-closes.
6. When the water level sensor has declared a blocked
drain (heating operation is shut down due to this fault)
and then the fault goes away after the gas heat is shut
down. If upon return to the next heat attempt (same
heat call) a blocked drain is sensed again within five
minutes after energizing the inducer for pre-purge, the
control will enter a one-hour lockout and the fault codes
“59”
(Blocked Drain) and
“10”
(soft lockout) will be dis-
played alternately as described above (A-D).
7. When the water level sensor has declared a 1-hr lock-
out after declaring a
Water Sensed
condition (heating
operation is shut down due to this fault) several times
consecutively. When the control enters lockout the fault
codes
“59”
(
Water Sensed
) and
“10”
(soft lockout)
will be displayed alternately as described above (A-D).
When multiple fault codes are present and are not part of
the seven exceptions noted above, the fault code dis-
played is resolved by priority. For example an unexpected
flame has a higher priority than a blocked drain. There-
fore, if both conditions are present at the same time, the
unexpected flame fault will be displayed until the condition
is corrected and then the blocked drain fault will be dis-
played (provided the fault condition is still present).
FAULT CODES
CODE Description
0 STANDBY
C COMPRESSOR ON
(COOLING OR HEAT-PUMP HEAT)
H GAS HEAT ON
F CONTINUOS FAN ON
10 1 HOUR LOCKOUT
11 FAILED IGNITION
12 LOW FLAME SENSE
13 FLAME LOST
14 UNEXPECTED FLAME
20 TWINNING FAULT
22 MAIN LIMIT OPEN
26 LINE AND NEUTRAL REVERSED
33 MRLC (MANUAL RESET LIMIT
CONTROL) (AKA ROLL-OUT) OPEN
55 PRESSURE SWITCH STUCK
CLOSED WHEN SHOULD BE OPEN
57 PRESS SWITCH STUCK OPEN
WHEN SHOULD BE CLOSED
58 WATER SENSE CIRCUIT OPEN
59 WATER SENSED
61 BLOWER FAULT – BLOWER
UNABLE TO RUN
93 INTERNAL CONTROL FAULT
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