18
11 NO PREVIOUS CODE – Status codes are
erased after 72 hours or can be manually
erased by putting setup switch SW1-1 in
the ON position and jumpering R, W/W1,
and Y/Y2 simultaneously until status code
#11 is ashed. Run system through a low-
heat, high-heat, or cooling cycle to check
system.
12 BLOWER ON AFTER POWER UP –
(115V OR 24V) – Normal operation.
Blower runs for 90 seconds, if unit is
powered up during a call for heat (R-
W/W1 closed) or when (R-W/W1 opens)
during the blower on-delay period.
13 LIMIT CIRCUIT LOCKOUT – Lockout
occurs if the limit or
ame rollout switch is
open longer than 3 minutes or 10
successive limit trips occurred during high-
heat. Control will auto-reset after 3 hours.
See code 33.
14 IGNITION LOCKOUT – System failed to
ignite gas and prove ame in 4 attempts.
Control will auto-reset after 3 hours. See
status code 34.
21 GAS HEATING LOCKOUT – Turn o
power and wait 5 minutes to retry. Check
for:
- Stuck closed gas valve relay on control.
- Miswire or short to gas valve wire.
22 ABNORMAL FLAME-PROVING SIGNAL
Flame is proved while gas valve is de-
energized. Inducer will run until fault is
cleared. Check 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:
- Short circuit in secondary voltage (24V)
wiring including thermostat leads.
Disconnect thermostat leads to isolate
short circuit.
32 LOW-HEAT PRESSURE SWITCH DID
NOT CLOSE OR REOPENED – If opens
during blower on-delay period, blower will
come on for the selected blower o-delay.
If opens within 5 minutes after ignition the
next heating cycle will be restricted to
high-heat. Check for:
- Proper vent sizing.
- Low inlet gas pressure (if LGPS used).
- Restricted combustion air supply.
- Disconnected or obstructed pressure
tubing.
- Defective or miswired pressure switches
- Excessive wind. If problem persists turn
setup switch SW1-3 ON.
- Plugged condensate drain.
- Water in vent piping, possible sagging
i
e.
33 LIMIT CIRCUIT FAULT – Indicates the
limit or ame rollout switch is open or the
furnace is operating in high-heat only
mode due to 2 successive low- or
medium-heat limit trips. Blower will run for
4 min. or until open switch remakes
whichever is longer. If open longer than 3
min., code changes to lockout #13. If
open less than 3 min.
status code #33
continues to ash until blower shuts o.
Flame rollout switch requires manual
reset. Check for:
- Proper rear air bae.
- Loose blower wheel.
- Defective switch or connections.
- Improper low- or medium-heat gas input
adjustment.
- Improper or misaligned limit and/or limit
shield.
- Stuck high-heat solenoid in gas valve.
34 IGNITION PROVING FAILURE – If ame is
not sensed during the trial for ignition
period, the control will repeat the ignition
sequence 3 more times before lockout #14
occurs. If ame signal is lost during the
blower on-delay period, blower will come on
for the selected blower o-delay. Check
the following items rst before proceeding
to the next step.
- Gas valve turned o.
- Manual shut-o valve.
- Green/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 ame sensor the
system can be operated in component test
mode. To check the igniter remove the R
thermostat connection from the control,
reset power, and put setup switch SW1-6 in
the ON position to start the component test.
Does the igniter glow orange/white by the
end of the 15 second warm-up period?
Unplug igniter harness from control and
repeat component test by turning setup
switch SW1-6 OFF and then back ON.
Check for 115V between pin 3 and
NEUTRAL-L2 on the control. Was 115V
present for the 15 second period?
Check connections and retry.
If current is near typical value
(4.0-6.0 nominal) and burners
will not stay on, repeat check
in high-heat. If burners will
still not stay on replace
control. If burners operate in
high-heat then switch to
medium-heat, check manifold
pressure. If OK, check
burner carryover and ame
sensor location.
Clean ame sensor with ne steel wool
and recheck current. Nominal current is
4.0 to 6.0 microamps.
Is current near typical value? Replace electrode.
Will main burners ignite and stay on? Replace furnace control.
Fixed.
NO
YES
YES
YES
NO
NO
15 BLOWER MOTOR LOCKOUT – Indicates
the blower failed to reach 250 RPM or the
blower failed to communicate within 30
seconds after being turned ON in two
successive heating cycles. Control will
auto-reset after 3 hours. See code 41.
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.
Reconnect the R thermostat lead and set
thermostat to call for heat. Connect
voltmeter across gas valve connections.
Does gas valve receive 24V?
Does gas valve open and allow gas to
ow?
Do the main burners ignite?
Do the main burners stay on?
Allow unit to drop to low-heat,
and check manifold pressure.
Repeat test to check for
intermittent operation.
Check that all gas valves are
turned on. Replace valve.
Check connections. If OK,
replace control.
Check for:
- Inadequate ame carryover
or rough ignition.
- Low inlet gas pressure.
- Proper ring rate.
- Air leakage around igniter
bracket.
Repeat call for heat and check ame
sensor current during trial for ignition
period. Is the DC microamps below 0.5?
YES
YES
YES
YES
YES
NO
NO
NO
NO
NO
NO
43 LOW-HEAT PRESSURE SWITCH OPEN
WHILE MEDIUM-HEAT PRESSURE
SWITCH IS CLOSED - Check for:
- Low-heat pressure switch stuck open.
- Disconnected or obstructed pressure
tubing.
- Improper pressure switch wiring.
- Low inlet gas pressure (if LGPS used).
- Plugged condensate drain.
- Water in vent piping, possible sagging
pipe.
A07582
58MVC
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