ICP N9MSB Series User Manual

SERVICE AND TECHNICAL SUPPORT MANUAL Gas Furnace: N9MSB
Specifications subject to change without notice.
26 440 04 4413 03
Figure 16
Troubleshooting Guide − Flow Chart
Is LED status light ON solid, alternately flashing bright
-dim-bright-dim like a
h
eartbeat, or flashing ON and OFF?
Is there 24V at 24VAC and COM?
Is there 115V at L1 and NEUTRAL?
Is the 24V fuse open?
Is door switch closed?
Replace transformer.
Replace door switch.
Is there 115V going to switch?
Close the door switch.
Is circuit breaker closed?
Check for continuity in wire from circuit breaker to furnace.
Close circuit breaker and go back to START.
Is LED status light alternately flashing bright
-dim-bright-dim like a heartbeat?
Determine status code. The status code is a
single or two digit number with the
first
number
determined by the number of
short flashes and the second
number
after
the plus (+) sign, the number
of long
flashes.
To recall a status code: Briefly (2 – 3 seconds) connect the
TEST/TWIN terminal
to the “C” thermostat terminal with a jumper wire
to begin status code recovery and
component test. If a previous status code is present, the code will repeat 4 times then go on to component test. If no previous code is present, a component test will begin without flashing any status codes.
Component Test Sequence: Gas valve
and humidifier will not be turned on. Inducer motor will start and remain on until the end of the blower test, then off. T
he
following components are on for 10 – 15 seconds each individually: hot surface igniter,
blower speeds: FAN (if present),
HEAT, COOL.
Was there a previous status code?
Go to section below for the flashed status code.
Does the control respond to W, Y1, Y/Y2, and G (24V
) thermostat signals?
Run system through a heat, or cooling cycle to check operation. Status codes are erased after 72 hours.
Is 24V present at W, Y1, Y/Y2 or G thermostat terminals on the furnace control?
Check room thermostat or interconnecting cable.
Disconnect all the thermostat wires from the furnace control.
Does the problem repeat when using a jumper wire?
Replace furnace control.
The thermostat is not compatible with the furnace control. Either install a ballast r
esistor, connect the C furnace control
thermostat terminal to the thermostat, or replace the thermostat.
YES
NO
YES
YES
YES
YES
YES
YES
YES
START
YES
YES
NO
NO
NO
NO
NO
NO
NO
NO
YES
NO
NO
Troubleshooting Guide
Replace furnace control.
YES
Inspect secondary voltage (24V) wiring, including thermostat leads for short circuit.
Replace fuse
NO
Is LED status light ON solid?
NO
YES
The control is locked out and will auto- reset after 1 hour. Lockout could be due to any of the following:
-
Flame sense circuit failure.
-
Gas valve relay stuck open.
-
Software check error.
Reset power to clear lockout. Replace control if code repeats.

ICP N9MSB Series Specifications

General

Brand	ICP
Model	N9MSB Series
Category	Furnace
Language	English