Diagnostic Code Section - International comfort products N9MP1 Service Manual

Single Stage Multi Position Furnace
Heartbeat
NO PREVIOUS CODE − Stored codes are erased
after 72 hours. Run system through a heating or
cooling cycle to check system.
LED OFF
No power
− Check 5A furnace control fuse
− Check circuit breaker or fuse
− Check door switch.
− Check 115V and 24V wiring
ON Solid
CONTROL CIRCUIT 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
2 PRESSURE SWITCH DID NOT OPEN −
Check for:
− Obstructed pressure tube.
− Pressure switch stuck closed.
3 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)
− Inadequate combustion air supply.
− Disconnected or obstructed pressure tubing
− Defective inducer motor.
− *LP Low pressure gas switch open
− Defective pressure switch.
− Excessive wind.
− Restricted vent.
* LP low pressure gas switch used in LP kit
440 08 2011 00

Diagnostic Code Section

4 LIMIT CIRCUIT FAULT − Indicates the limit, flame
rollout switch is open. Blower and inducer will run
until open switch remakes. If open longer than
2 minutes, code changes to lockout #7. If open less
than 2 min. status code #4 continues to flash
until blower shuts off. Flame rollout switch requires
manual reset. Check for:
− Dirty filter or restricted duct system.
− Loose blower wheel.
− Defective blower motor or capacitor.
− Inadequate combustion air supply
(flame rollout switch open).
− Restricted vent.
− Proper vent sizing.
− Excessive wind.
5 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.
6 IGNITION PROVING FAILURE − If flame is not
sensed during the trail for ignition period, the control
will repeat the ignition sequence 3 more times
before a lockout #6 + 1 occurs. If flame signal is
lost during the blower on−delay period, blower
blower will come on for the selected blower off
delay. Check the following items first before
proceeding to the next step
− Gas value turned ON.
− Open.
− 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 flame sensor.
6 + 1
IGNITION LOCKOUT − System failed to ignite gas
and prove flame in 4 attempts. Control will
auto−reset after 3 hours. See status code 6.
7 LIMIT CIRCUIT LOCKOUT − Lockout occurs if the
limit, flame rollout is open longer than 2 minutes.
Control will auto−reset after 1 hour. See code 4.
8 GAS HEATING LOCKOUT − Turn off power and
wait 5 minutes to retry. Check for:
− Stuck closed gas valve relay on control.
− Miswire or short to gas valve wire.
Service Manual
9 NOT USED ON SINGLE STAGE
10 Check for correct line voltage polarity. If
units are twinned. Check for proper low
voltage (24V) transformer phasing.
37