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18
11
NO PREVIOUS CODE – Stored codes
are erased after 72 hours. On RED LED
boards stored status codes can also be
erased whenever power (115V or 24V)
is interr
upted. Run system through a
heating or cooling cycle to
check system.
12 BLO
WER ON AFTER PO
WER UP –
(115V OR 24V) – Normal operation.
Bl
ow
er r
uns for 90 seconds, if unit is
powered up during a call for heat (R-W
closed) or when (R-W opens) during th
e
blower on-delay period.
13 LIMIT CIRCUIT LOCKOUT – Lockout
occurs if the limit or flame rollout switch is
open longer than 3 minutes. Control will
auto-r
eset after 3 hours.
See code 33
.
14 IGNITION LOCKOUT – System failed to
ignite gas and prove flame in 4
attempts.
Control will auto-reset after 3 hours.
See status code 34.
21 GAS HEATING LOCKOUT – Tur
n off
power and wait 5 minutes to retry.
Chec
k for:
- Stuck closed gas valve relay
on control.
- Miswire or short to gas valve wire.
22 ABNORMAL FLAME-PRO
VING SIGNAL
Flame is proved while gas valve is de-
energiz
ed.
Inducer will run until fault is
cleared. Chec
k for:
- Stuck open or leaky gas valve.
23 PRESSURE SWITCH DID NOT OPEN
Check for:
- Obstructed pressure tube.
- Pressure switch stuck closed.
24
SECONDARY VOLTAGE FUSE IS OPEN
Check for:
-Shor
t circuit in secondary
vo
ltage (24V)
wiring including thermostat leads.
D
isconnect thermostat leads to isolate
short circuit.
31 PRESSURE SWITCH DID NOT CLOSE
OR REOPENED – If open longer than 5
minutes, inducer shuts off for 15 minutes
before retry. If opens during blower on-
delay period, blower will come on for the
selected blower off-delay. Check for:
- Proper vent sizing.
- Low inducer voltage (115V).
- Low inlet
gas pressure
(if LGPS used).
- Inadequate comb
ustion air supply.
-D
isconnected or obstr
ucted pressure
tubing.
-D
efective inducer motor.
-D
efective pressure switch.
- Excessive wind.
-R
estr
icted vent.
33 LIMIT CIRCUIT FAU
LT – Indicates the
limit or flame rollout switch
is
open.
Blower
will run for 4 minutes or until open sw
itc
h
remakes whiche
ver is longer. If open
longer than 3 minutes, code changes to
lockout #13. If open less than 3 min.
status code #33 continues to flash until
blower shuts off. Flame rollout switch
requires manual reset. Check for:
- Dirty filter or restricted duct system.
- Loose b
lower wheel.
- Defective switch or connections.
-D
efectiv
e blower motor or capacitor.
-
Inadequate combustion air supply
(flame rollout s
witch open).
-R
estricted vent.
- Proper vent sizing.
- Excessive wind.
- Blower motor on incorrect speed tap.
- Input rate to fur
nace set too high.
34 I
GNITION PROVING FAILURE – If
flame
is not sensed during the trial f
or ignition
per
iod,
the control will repeat the ignition
sequence 3 more times before lo
ck
out
#14 occurs. If flame signal is lost during
the blower on-delay period, blower wil
l
come on for the selected blower off-delay.
Check the following items first before
proceeding to the next step.
- Gas valve turned off.
- Manual shut-off valve.
-G
reen/Yellow
wire
MUST be connected
to furnace sheet metal.
- Flame sensor must not be grounded.
To determine whether the problem is in
the gas valve,
igniter, or flame sensor the
system can be operated in the component
test mode to chec
k the igniter. First
remove the R thermostat connection from
the control and initiate the component
test sequence. Does the igniter glow
orange/white by the end of the 15 second
warm-up period?
Unplug igniter harness from control and initiate
another component test sequence. Check
for 115V between pin 1 and NEUTRAL-L2 on
the control. Was 115V present for the 15
second per
iod?
Reconnect the R thermostat lead and set
ther
mostat to call for heat. Connect voltmeter
across gas va
lve
connections. Does gas valve
receiv
e 24V?
Does gas valv
e open and allow gas to flow?
Do the main burners ignite?
Do the main b
urners stay on?
Repeat call f
or heat and check flame sensor
current dur
ing trial for ignition period. Is the
DC microamps bel
ow 0.5?
Is current near typical value?
Will main b
urners ignite and stay on?
Fix
ed.
Clean flame sensor with fine steel wool and
recheck current. Nominal current is 4.0 to 6.0
microamps.
45 CONTROL CIRCUITRY LOCKOUT
Auto-reset after 1 hour lockout due to:
- Flame circuit failure.
- Gas valve relay stuck open.
- Software check error.
Reset power to clear lockout. Replace
control if code repeats.
Replace furnace control.
Check for continuity in the harness and
igniter.
Replace defective component.
Check connections. If OK, replace control.
Check that all gas valves are turned on.
Replace v
al
ve.
Check for:
-
Inadequate flame carr
yov
er or rough
ignition.
- Low inlet gas pressure.
- Proper firing rate.
Allow blow
er to come on and repeat test to
check for intermittent operation.
Chec
k connections and retry. If current is
near typical
value (4.0-6.0 nominal) and
burners will not stay on, replace control.
Replace electrode.
Replace furnace control.
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A05096
58MCB