Haier GE NF97DM User manual

31-5000724 Rev. 0 11-22 GEA
NF97DM
97% Downow Modulating
Variable Speed Gas Furnace
Service
Manual
READ CAREFULLY.
KEEP THESE INSTRUCTIONS.

Page 2 31-5000724 Rev. 0
SERVICE MANUAL
NF97DM Gas Furnace
Table of Contents
Technical Specications - NF97DM.............................3
Parts Arrangement.......................................................6
Unit Components.........................................................7
Conguring Unit Size Codes .....................................15
Placement and Installation ........................................31
Joint Cementing Procedure.......................................32
Venting Practices.......................................................33
Vent Piping Guidelines ..............................................35
For the Province of Ontario, Horizontal
Sidewall Vent Applications Only ................................44
Addendum for All Provinces of Canada.....................44
Condensate Piping ....................................................45
Start-Up .....................................................................49
Heating System Service Checks ...............................50
Typical Operating Characteristics..............................54
Maintenance..............................................................55
Wiring and Sequence of Operation ...........................58
Field Wiring Applications with
Conventional Thermostat ..........................................61
Sequence of Operation and
Troubleshooting Flow Chart ......................................64
This is a safety alert symbol and should never be ignored. When you see this symbol on labels or in manuals, be alert to
the potential for personal injury or death.
Electric shock hazard.
Can cause injury or death. Before attempting
to perform any service or maintenance, turn
the electrical power to unit OFF at disconnect
switch(es). Unit may have multiple power
supplies.
WARNING
As with any mechanical equipment, contact with sharp
sheet metal edges can result in personal injury. Take
care while handling this equipment and wear gloves and
protective clothing.
CAUTION
Improper installation, adjustment, alteration, service or
maintenance can cause property damage, personal injury
or loss of life. Installation and service must be performed
by a licensed professional HVAC installer (or equivalent),
service agency or the gas supplier.
WARNING
NF97DM series units are high-e󰀩ciency upow, horizontal
right and left) gas furnaces equipped with variable capacity
gas valve, variable speed combustion air inducer and
variable speed indoor blower motor. All models are designed
only for direct vent (dual pipe) venting system. NF97DM
units are available in heating inputs from 66,000 to 110,000
Btuh (19.3 to 32.2 kW) and cooling applications from 2 to 5
tons (7.0 kW to 17.5 kW). Refer to Technical Specications
for proper sizing.
Units are factory-equipped for use with natural gas. Kits are
available for conversion to LPG operation. All NF97DM units
meet the California Nitrogen Oxides (NOx) Standards and
California Seasonal E󰀩ciency requirements.
All specications in this manual are subject to change.
Procedures outlined in this manual are presented as
recommendations only and do not supersede or replace
local or state codes. In the absence of local or state codes,
the guidelines and procedures outlined in this manual
(except where noted) are recommendations only and do not
constitute code.

Page 3
31-5000724 Rev. 0
PHYSICAL AND ELECTRICAL DATA
Model Input
(Btuh)
Output *
(Btuh)
AFUE
(ICS)
Nominal*
Cooling
Capacity
Gas
Inlet
(in.)
Volts-
Hertz-
Phase
Max. Time
Delay
Breaker or
Fuse
Nominal
F.L.A.
Trans.
(V.A.)
Approx.
Shipping
Weight
(lbs.)
DOWNFLOW
NF97D070M3B 66,000 64,000 97.0% 3 Tons 1/2 120-60-1 15 7.7 40 140
NF97D090M4C 88,000 85,000 97.0% 4 Tons 1/2 120-60-1 15 10.1 40 165
NF97D110M5C 110,000 107,000 97.0% 5 Tons 1/2 120-60-1 20 12.8 40 174
Note: For vent length and clearances to combustibles, please reference installation instructions.
* At full capacity
Technical Specications - NF97DM
MODEL NUMBER GUIDE
MAJOR/MINOR REVISION
CABINET WIDTH
B - 17.5
C - 21.0
NOMINAL CFM
3 - 1200 CFM
4 - 1600 CFM
5 - 2000 CFM
DESIGN VARIANT
M - VARIABLE SPEED MODULATING
BRAND
N - GE
PRODUCT
F - FURNACE, GAS
AFUE
97 - 97% EFFICENCY
APPLICATION
D - DOWNFLOW
HEATING INPUT (1000 BTU/HR)
70, 90, 110,
NNFF9797 DDMM55CCXXXX110110

Page 4 31-5000724 Rev. 0
BLOWER PERFORMANCE: RETURN INLET
Model
Motor
Size
(hp)
Blower
Size
Temp
Rise
F°
Heating
CFM @ 0" - 0.8" w.c. Cooling
Stages
Speed
Adjustment
Cooling
CFM @ 0" - 0.8" w.c.
* * 40%
Input
70%
Input
100%
Input Low Medium Low
Medium
High
High
Default
DOWNFLOW
NF97D070M3B
1/2 HP 10 x 9
50 - 80
Max.
Input
+15% 543 830 1118 2nd
Stage
+10% 910 1075 1232 1366
+7.5% 516 778 1041 Default 846 963 1126 1267
Default 489 726 963 -10% 759 889 986 1154
35 - 65
Min.
Input
1st
Stage
+10% 625 788 890 998
-7.5% 467 687 908 Default 573 711 830 894
-15% 444 649 853 -10% 520 619 714 822
NF97D090M4C
1/2 HP 10 x 9
60 - 90
Max.
Input
+15% 756 1033 1309 2nd
Stage
+10% 924 1083 1218 1386
+7.5% 713 971 1230 Default 835 1000 1136 1259
Default 669 910 1150 -10% 751 890 1028 1145
35 - 65
Min.
Input
1st
Stage
+10% 610 771 902 1035
-7.5% 599 845 1091 Default 549 690 808 923
-15% 530 781 1032 -10% 466 623 721 812
NF97D110M5C
1 HP 11 x 11
50 - 80
Max.
Input
+15% 906 1475 2045 2nd
Stage
+10% 1337 1583 1792 2011
+7.5% 835 1380 1926 Default 1222 1440 1629 1867
Default 764 1285 1807 -10% 1098 1273 1473 1678
35 - 65
Min.
Input
1st
Stage
+10% 922 1093 1264 1442
-7.5% 707 1193 1679 Default 830 965 1129 1289
-15% 650 1101 1551 -10% 738 860 1034 1156
** See installation instructions for proper blower setup

Page 5
31-5000724 Rev. 0
ACCESSORY LIST
Catalog Number Description
Natural to LP Kits
68W77 Modulating 97% (including gas valve)
Downow Combustible Flooring Base
11M60 17.5" B Width
11M61 21.0" C Width
Flush Mount Termination (90% Furnaces only) US Only
51W11 2” & 3.0” Vent
Concentric Vent Kit (90% Furnaces only) US Only
71M80 1-1/2” Vent Version (United States)
69M29 2” Vent Version (United States)
60L46 3” Vent Version (United States)
Concentric Vent Kit Canada
44W92 1-1/2” & 2” Vent
44W93 3.0” Vent
For vent length and clearances to combustibles, please reference installation instructions.

Page 6 31-5000724 Rev. 0
Parts Arrangement
Figure 1.
Burner
Access
Panel
Blower
A
ccess
Panel
Combustion
Air Inducer
Control
Box
Blower
Assembly
Burner Box
Assembly
Blower Deck
Heat Exchanger
Assembly
Gas Valve
and Manifold
Primary
Limit
Cabinet

Page 7
31-5000724 Rev. 0
Unit Components
NF97DM unit components are shown in Figure 1. The gas
valve, combustion air inducer and burners can be accessed
by removing the access panel. Electrical components are in
the control box (Figure 2) found in the blower compartment..
Electrostatic discharge can a󰀨ect
electronic components. Take
precautions to neutralize electrostatic
charge by touching your hand and
tools to metal prior to handling the
control.
CAUTION
Control Box
Control Transformer (T1)
A transformer located in the control box provides power to the
low voltage section of the unit. Transformers on all models
are rated 40VA with a 120V primary and a 24V secondary.
INTEGRATED
CONTROL TRANSFORMER
CIRCUIT
BREAKER
DOOR
INTERLOCK
SWITCH
Figure 2. Control Box
Door Interlock Switch (S51)
A door interlock switch rated 14A at 125VAC is wired in
series with line voltage. When the inner blower access panel
is removed the unit will shut down.
Circuit Breaker (CB8)
A 24V circuit breaker is also located in the control box. The
switch provides overcurrent protection to the transformer
(T1). The breaker is rated 3A at 32V. If the current exceeds
this limit the breaker will trip and all unit operation will
shutdown. The breaker can be manually reset by pressing
the button on the face. See Figure 3.
PRESS TO RESET
Figure 3. Circuit Breaker CB8
Shock hazard.
Disconnect power before servicing. Integrated control
is not eld repairable. If control is inoperable, simply
replace entire control.
Can cause injury or death. Unsafe operation will result
if repair is attempted.
WARNING
Integrated Control (A92)
Units are equipped with a variable capacity integrated
control. The control can operate with a 24V conventional
single or two-stage thermostat. The system consists of an
ignition / blower control (Figure 4 and Figure 5) with control
pin designations (Table 1 through Table 2) and an ignitor.
The control and ignitor work in combination to ensure
furnace ignition and ignitor durability. The control provides
gas ignition, safety checks and indoor blower control with
two-stage gas heating. The furnace combustion air inducer,
gas valve and indoor blower are controlled in response to
various system inputs such as thermostat signal, pressure
and limit switch signal and ame signal. The control features
a seven-segment LED display, indicating furnace status
(including indoor blower) and error codes. The LED ashes
in single digits. For example, using the table on Page 16,
under CODE, an “E” followed by “2” followed by “5” followed
by “0”, the limit switch circuit is open. The control also has
two unpowered (dry) 1/4” contacts for a humidier and a 120
volt accessory terminal. Both rated at (1) one amp each.

Page 8 31-5000724 Rev. 0
Pin # Function
1Not Used
2High Fire Pressure Switch
3Rollout Switch In
4Ground
524V Hot
6Primary Limit In
7Gas Valve
8Gas Valve Common
924V Neutral
10 Ground
11 Primary Limit Switch Out
12 Low Fire Pressure Switch
Table 1. Control 12-Pin Terminal Designation
Pin # Function
1Data Input From Motor
2Common
3Not Used
4Data Output To Motor
55 Volt Bias Supply
6Not Used
Table 2. Control 6-Pin Terminal Designation
Electronic Ignition
At the beginning of the heat cycle the integrated control
monitors the low re combustion air inducer pressure switch.
The control will not begin the heating cycle if the low re
pressure switch is closed (by-passed). Likewise the control
will not begin the high re heating cycle if the high re
pressure switch is closed, and will remain in low re heat.
However, if the high re pressure switch closes during the low
re heat pre-purge, the control will allow high re heat. Once
the low re pressure switch is determined to be open, the
combustion air inducer is energized on ignition speed. When
the di󰀨erential in the pressure switch is great enough, the
pressure switch closes and a 15-second pre-purge begins.
If the switch is not proven within 2-1/2 minutes, the inducer
is de-energized and the control will initiate vent calibration.
If the vent calibration is unsuccessful the control goes into
a 5 minute delay. The control will attempt vent calibration
3 more times before going into a 1 hour soft lockout. After
the 15 second pre-purge period the ignitor warms up for
20 seconds. The gas valve then opens for a 4-second trial
for ignition. The ignitor stays energized during this trial until
ame is sensed. If ignition is not proven during the 4-second
trial for ignition, the control will try four more times with an
inter purge and warm-up time between trials of 35 seconds.
After a total of ve trials for ignition (including the initial trial),
the control goes into Watchguard-Flame Failure mode. After
a 60-minute reset period, the control will begin the ignition
sequence again.
Thermostat Selection Modes
See Table 3 for DIP switch settings
The control can be made to operate in three modes: variable
capacity, three-stage timed or two-stage. The variable
capacity and two-stage modes are only operational with
a two-stage thermostat. The thermostat selection is made
using dip switches one and / or two (Figure 4) and must be
positioned for the particular application.
Variable Capacity
Using a two-stage thermostat the system will operate in a
variable capacity sequence mode. In this mode, the control
will vary the ring rate anywhere between 35% and 100% of
full capacity. The indoor blower will be automatically adjusted
accordingly to provide the appropriate airow at any rate. On
the initial call for low re, the furnace will operate at 35% and
will remain there until the heat call is satised or a call for
high re is initiated. If there is a call for high re the rate will
increase by 10% if the current rate is above 60%. However,
if the current rate is below 60% the rate will increase to 70%.
After this initial rate increase to 70% capacity, the furnace
will increase rate by 10% every 5 minutes while a high re
heat call is present. If the high re heat call is satised but
the low re heat call is still present, the furnace will remain at
the current ring rate until the demand is satised or another
call for high re is initiated.
Three-Stage Timed Operation
Using a single-stage thermostat the system will operate
in a three stage timed mode. Upon a call for heat and a
successful ignition, the combustion air inducer will operate
at 35% and the indoor blower will adjust to the appropriate
cfm. After a eld selectable 7 or 12 minute delay period, the
inducer RPM will increase and the unit will operate at 70%.
The indoor blower will adjust to the appropriate cfm. After
a factory set non-adjustable 10 minute delay expires the
furnace will increase rate to 100%. The indoor blower will
adjust to the appropriate cfm.
Two-Stage Operation
The system will also operate in conventional two-stage
mode. While in two-stage mode, the furnace will re on low
re (70% rate). The combustion air inducer will operate at
70% and the indoor blower will adjust to the appropriate
cfm. The unit will switch to high re on a W2 call from the
thermostat. After a 30 second recognition period (during
which the integrated control will receive a continuous W2
call) expires the furnace will increase to 100% rate. The
inducer will increase to 100% speed and the indoor blower
will adjust to appropriate cfm. If there is a simultaneous call
for rst and second stage heat, the unit will re on rst stage
heat and switch to second stage heat after 30 seconds of
operation.

Page 9
31-5000724 Rev. 0
FLAME
SENSE
COMBUSTION
AIR INDUCER
CONNECTOR
DIP SWITCHES
OUTDOOR AIR
SENSOR
TERMINALS
DISCHARGE AIR
SENSOR
TERMINALS
W915
W951
W914
INDOOR
BLOWER
CONNECTOR
EAC
HUM
LINE VOLTAGE
TERMINALS
NEUTRAL
TERMINALS
IGNITOR
CONNECTOR
7-SEGMENT
DIAGNOSTIC LED
DIAGNOSTIC
PUSH BUTTON
FACTORY TEST
HEADER PINS.
FACTORY USE ONLY.
E43 OUTDOOR
(NOT USED)
E44 INDOOR
(NOT USED)
W915 Y1 TO Y2
W951 R TO O
W914 R TO DS
E43 E44
E3
RS-BUS LINK (E3)
I+ = DATA HIGH CONNECTION
I - = DATA LOW CONNECTION
RS-BUS OUTDOOR (E43, not used)
R = 24VAC
I + = DATA HIGH CONNECTION
I - = DATA LOW CONNECTION
C = 24VAXC COMMON
RS-BUS INDOOR (E44, not used)
R = 24VAC
I + = DATA HIGH CONNECTION
I - = DATA LOW CONNECTION
C = 24VAXC COMMON
1/4” QUICK CONNECT TERMINALS
HUM = 120 VAC OUTPUT TO HUMIDIFIER
XMFR = 120 VAC OUTPUT TO TRANSFORMER
LI = 120 VAC INPUT TO CONTROL
CIRC = 120 VAC OUTPUT TO CIRCULATING BLOWER
EAC = 120 VAC OUTPUT TO ELECTRICAL AIR CLEANER
NEUTRALS = 120 VAC NEUTRAL
THERMOSTAT CONNECTIONS (E7)
DS = DEHUMIDIFICATION SIGNAL
W2 = HEAT DEMAND FROM 2ND STAGE T/STAT
W1 = HEAT DEMAND FROM 1ST STAGE T/STAT
R = CLASS 2 VOLTAGE TO THERMOSTAT
G = MANUAL FAN FROM THERMOSTAT
C = THERMOSTAT SIGNAL GROUNCONNECTED TO
TRANSFORMER GRD (TR) & CHASIS GROUND (GRD)
Y1 = THERMOSTAT 1ST STAGE COOL SIGNAL
Y2 = THERMOSTAT 2ND STAGE COOL SIGNAL
O = THERMOSTAT SIGNAL TO HEAT PUMP REVERSING
VALVE
H = 24V HUMIDIFIER OUTPUT
Figure 4. Integrated Control

Page 10 31-5000724 Rev. 0
Figure 5. Integrated Control Conguration Guide

Page 11
31-5000724 Rev. 0
Heating Operation DIP Switch Settings -- Figure 4
Switch 1 -- Thermostat Selection -- This unit may be used
with either a single-stage or two-stage thermostat. The
thermostat selection is made using a DIP switch which must
be properly positioned for the particular application. The
DIP switch is factory-positioned for use with a two-stage
thermostat. If a single-stage thermostat is to be used, the
DIP switch must be repositioned. See Table 3.
NOTE: All DIP switches are factory shipped in the “OFF”
position.
Switch 2 -- Operating Mode with Two-Stage Thermostat
-- If a two-stage thermostat is used, the furnace can operate
in either variable-capacity or conventional two-stage mode.
When variable-capacity mode is selected, the ring rate
of the unit is varied to maximize comfort. Conventional
twostage mode is the factory default setting. See Table 3.
Switch 3 -- Second-Stage Heat On Delay -- If a singlestage
thermostat is used, the integrated control can be used to
energize second-stage heat after either 7 minutes or 12
minutes of rst-stage heat operation. See Table 3.
Switches 4 and 5 -- Blower-O󰀨 Delay -- The blower-on
delay of 45 seconds is not adjustable. The blower-o󰀨 delay
(time that the blower operates after the heating demand
has been satised) can be adjusted by moving switches 4
and 5 on the integrated control. The unit is shipped from the
factory with a blower-o󰀨 delay of 90 seconds. The blower o󰀨
delay a󰀨ects comfort and is adjustable to satisfy individual
applications. Adjust the blower o󰀨 delay to achieve a supply
air temperature between 90° and 110°F at the exact moment
that the blower is de-energized. Longer o󰀨 delay settings
provide lower supply air temperatures; shorter settings
provide higher supply air temperatures. Table 4 provides
the blower o󰀨 timings that will result from di󰀨erent switch
settings.
Blower O󰀨 Delay
(Seconds) Switch 4 Switch 5
60 O󰀨 On
90 (Factory) O󰀨 O󰀨
120 On O󰀨
180 On On
Table 4. Blower O󰀨 Delay Switch Settings
Switches 6 and 7 - Continuous Indoor Fan Operation -
Blower Speed - The unit is shipped from the factory with the
DIP switches positioned for medium low (38%) speed during
continuous indoor blower operation. Continuous fan setting
is 38% of cool setting and is not adjustable.
Switches 8 and 9 -- Cooling Mode Blower Speed --
Switches 8 and 9 are used to select cooling blower motor
speed. The unit is shipped from the factory with the DIP
switches positioned for high speed (4) indoor blower motor
operation during the cooling mode. Table 5 provides the
cooling mode blower speeds that will result from di󰀨erent
switch settings. Refer to blower tables at the front of this
manual for corresponding cfm values.
Speed Switch 8 Switch 9
1 - Low On On
2 - Medium Low O󰀨 On
3 - Medium High On O󰀨
4 - High (Factory) O󰀨 O󰀨
Table 5. Cooling Mode Blower Speeds
Switches 10 and 11 -- Cooling Mode Blower Speed
Adjustment -- Switches 10 and 11 are used to select
blower speed adjustment settings. The unit is shipped from
the factory with the DIP switches positioned for NORMAL
(no) adjustment. The DIP switches may be positioned to
adjust the blower speed by +10% or -10% to better suit the
application. Table 6 provides blower speed adjustments
that will result from di󰀨erent switch settings. Refer to blower
tables at the front of this manual for corresponding cfm
values. With switches 10 and 11 set to ON, motor will bypass
ramping proles and all delays and immediately upon a call
for cool, run at COOLING speed selected. LED will continue
Operation Thermostat Switch 1 Switch 2 Switch 3
Variable Capacity Heat
(40% to 100%) Two Stage O󰀨 On O󰀨
Three Stage Heat
(40%, 70%, 10%) Single Stage On O󰀨
2nd stage delay
OFF = 7 minutes
ON = 12 minutes
3rd stage delay
10 minutes xed
Two Stage Heat
(W1 70%, W2 100%) Single Stage O󰀨 O󰀨 O󰀨
Table 3.

Page 12 31-5000724 Rev. 0
to operate as normal. This mode is used to check motor
operation.
Adjustment Switch 10 Switch 11
+10% (approx.) On O󰀨
NORMAL (Factory) O󰀨 O󰀨
-10% (approx.) O󰀨 On
MOTOR TEST On On
Table 6. Blower Speed Adjustment
Switches 12 and 13 -- Cooling Mode Blower Speed
Ramping -- Switches 12 and 13 are used to select cooling
mode blower speed ramping options. Blower speed ramping
may be used to enhance dehumidication performance. The
switches are factory set at option A which has the greatest
e󰀨ect on blower motor performance. Table 7 provides the
cooling mode blower speed ramping options that will result
from di󰀨erent switch settings. The cooling mode blower
speed ramping options are detailed below.
Ramping Option Switch 12 Switch 13
A (Factory) O󰀨 O󰀨
B On O󰀨
C O󰀨 On
DOn On
Table 7. Cooling Mode Blower Speed Ramping
Ramping Option A (Factory Selection)
• Motor runs at 50% for 30 seconds.
• Motor then runs at 82% for approximately 7-1/2 minutes.
• If demand has not been satised after 7-1/2 minutes,
motor runs at 100% until demand is satised.
• Once demand is met, motor runs at 50% for 30 seconds
then ramps down to stop.
OFF
OFF
1/2 MIN
50% CFM
COMPRESSOR DEMAND
7 1/2 MIN
82% CFM
100%
CFM
1/2 MIN
50% CFM
Ramping Option B
• Motor runs at 82% for approximately 7-1/2 minutes.
If demand has not been satised after 7-1/2 minutes,
motor runs at 100% until demand is satised.
• Once demand is met, motor ramps down to stop.
OFF
OFF 82%CFM 100% CFM
COMPRESSOR DEMAND
7 1/2 MIN
Ramping Option C
• Motor runs at 100% until demand is satised.
• Once demand is met, motor runs at 100% for 45 seconds
then ramps down to stop.
OFF
OFF 100% CFM 100% CFM
45 SEC.
COMPRESSOR
DEMAND
Ramping Option D
• Motor runs at 100% until demand is satised.
• Once demand is met, motor ramps down to stop.
OFFOFF 100% CFM
COMPRESSOR
DEMAND
Switches 14 through19 -- Heating Mode Blower Speed
-- Switches 14 through 19 are used to select heating mode
blower motor speeds. These switches are factory set at
the OFF position which provides 100 % of normal speed
during HIGH HEAT demand, 70% of normal speed during
MIDRANGE HEAT demand and 40% of normal speed
during LOW HEAT demand. Switches 14, 15 and 16 are
used to adjust the LOW FIRE blower motor speed. Switches
17, 18 and 19 are used to adjust the HIGH FIRE blower
motor speed. Figure 6 and Table 8 and Table 9 provides the
heating mode blower speeds that will result from di󰀨erent
switch settings. Figure 6 indicates the e󰀨ect the DIP switch
settings have upon the heating airow at various furnace
ring rates.
Refer to blower tables at the front of this manual for
corresponding cfm values.
Thermostat
Demand
Blower Speed
Adjustments
DIP Switch Settings
14 15 16
Low Heat
(R to W1)
+15% On O󰀨 On
+7.5% On O󰀨 O󰀨
Normal O󰀨 O󰀨 O󰀨
-7.5% On On O󰀨
-15% On On On
Table 8. Low Heat Blower Speeds
Thermostat
Demand
Blower
Speed
Adjustments
DIP Switch Settings
14 15 16
High Heat
(R to W1 & W2)
+15% On O󰀨 On
+7.5% On O󰀨 O󰀨
Normal O󰀨 O󰀨 O󰀨
-7.5% On On O󰀨
-15% On On On
Table 9. High Heat Blower Speeds

Page 13
31-5000724 Rev. 0
Figure 6.
Low Fire
Dip Switches
14, 15, 16
High Fire
Dip Switches
17, 18, 19
Airflow Determination
Identify blower speed adjustment points at low and high fire
Airflow will lie on straight line between these two points and will fall within
the shaded area as shown
EXAMPLE -7.5% at low fire +7.5% at high fire
35% 50% 60% 70% 80% 90% 100%
RATE (%)
+15%
+7.5%
-7.5%
-15%
Nominal
-15%
Nominal
-7.5%
+7.5%
+15%
Increasing
Airflow
On-Board Link W914 DS to R (Figure 4)
On-board link W914, is a clippable connection between
terminals DS and R on the integrated control. W914 must
be cut when the furnace is installed with either the zone
control or a thermostat which features humidity control. If
the link is left intact the PWM signal from the control will be
blocked and also lead to control damage. Refer to Table 13
for operation sequence in applications including NF97DM,
a thermostat which features humidity control and a single-
speed outdoor unit. Table 14 gives the operation sequence
in applications with a two-speed outdoor unit.
On-Board Link W951 R to O (Figure 4)
On-board link W951 is a clippable connection between
terminals R and O on the integrated control. W951 must
be cut when the furnace is installed in applications which
include a heat pump unit and a thermostat which features
dual fuel use. If the link is left intact, terminal “O” will remain
energized eliminating the HEAT MODE in the heat pump.
On-Board Link W915 Y1 to Y2 (Figure 4)
On-board link W915 is a clippable connection between
terminals Y1 and Y2 on the integrated control. W915 must
be cut if two-stage cooling will be used. If the link is not cut
the outdoor unit will operate in second-stage cooling only.
Diagnostic LED (Figure 4)
The seven-segment diagnostic LED displays operating
status, target airow, error codes and other information. LED
codes are listed on Page 16.
Diagnostic Push Button (Figure 4)
The diagnostic push button is located adjacent to the seven-
segment diagnostic LED. This button is used to enable the
Error Code Recall mode and the Field Test mode. Press the
button and hold it to cycle through a menu of options. Every
ve seconds a new menu item will be displayed. When
the button is released, the displayed item will be selected.
Once all items in the menu have been displayed, the menu
resumes from the beginning until the button is released.
Error Code Recall Mode
Select ”E” from the menu to access the most recent 10 error
codes. Select “c” from the Error Code Recall menu to clear
all error codes. Button must be pressed a second time while
“c” is ashing to conrm command to delete codes. Press
the button until a solid “≡” is displayed to exit the Error Code
Recall mode.
Field Test Mode
Use the diagnostic push button to scroll through the menu as
described above. Release the button when the LED ashes
“-” to select the Field Test mode.
While in the Field Test mode the technician can:
• Initiate furnace ignition and move to and hold low-re
rate by applying a R to W1 jumper.
• Initiate furnace ignition sequence and move to and hold
high-re rate by applying a jumper from R to W1 and
W2.

Page 14 31-5000724 Rev. 0
• Initiate furnace ignition sequence and move to and hold
mid-re rate by applying a jumper to R and W2.
• Apply then remove the jumper from R to W1 and W2 to
change the ring rate from low re to mid re and high
re.
• A vent calibration sequence can be initiated even if a
thermostat signal is not present. Press and hold the push
button until a solid “C” is displayed. Release the button
and calibration will begin. The furnace will perform the
high-re and low-re pressure switch calibrations and
display “CAL”. After calibration, the LED will return to the
ashing “-” display.
During Field Test mode operation, all safety switches
are still in the circuit (they are not by-passed) and indoor
blower performance and timings will match DIP switch
selections. Current furnace ring rate, indoor blower CFM
and ame signal will be displayed. To exit the Field Test
mode, press and hold the button. The menu will resume
from the beginning. Also, cycle the main power to exit the
Field Test mode. The integrated control will automatically
exit the Field Test mode after 45 minutes of operation.
These options are displayed on the menu when the button is pressed during normal operation
Display Action (when button is released)
No change (idle) Remain in idle mode
Solid “E” Enter diagnostic mode
Solid “-” Enter eld test mode
NOTE - No change implies the display will continue to show whatever is currently being displayed for normal operation
Table 10. Idle Menu Options
These options are displayed when the button is used in Field Test Mode
Display Action (when button is released)
No change (blinking “-”) Remain in eld test mode
Solid “-” Exit eld test mode
Solid “c” Start pressure switch calibration
Table 11. Field Test Menu Options
These options are displayed when the button is used in diagnostic recall mode
Display Action (when button is released)
No change (displaying error history) Remain in diagnostic recall mode
Solid (3 horizontal bars) Exit diagnostic recall mode
Solid “c” Clear error history
Once the button is released to clear the error history a blinking “c” will be shown on the display for up to 10 seconds. During this
time the user must press and release the button one additional time to conrm the action of deleting the error history. Once the error
history is deleted it cannot be recovered.
Table 12. Diagnostic Recall Menu Options

Page 15
31-5000724 Rev. 0
To enter Program
Unit Capacity/
Size mode: Push
and hold button
next to 7-segment LED display until solid
“P” symbol appears. Release button.
IMPORTANT: Field replacement controls
may need to be manually congured to
validate furnace unit size code.
UNIT SIZE
CODE FURNACE MODEL
7NF97D070M3B
9NF97D090M4C
11 NF97D110M5C
Furnace control
in IDLE mode (No
heating, cooling, or
indoor fan operation)
Turn room thermostat to OFF.
When the correct unit size code is displayed, release
button. Selected code will ash for 10-second period.
During that period, press and hold button for 5 seconds.
Integrated control will store code in memory and will
automatically exit Field Test mode and reset. (If second
period expires or button is held less than 5 seconds,
control will automatically exit Field Test mode and go
into Idle mode without storing unit size code. If this
happens, programming function must be repeated.)
Verify that the selected unit size code is correct and
stored in non-volatile memory by cycling the 24 volt
power to the furnace control. (At 24 volt power-up of
the furnace control, the 7-segment LED will display a
unit size code. If three horizontal bars display, the board
does not recognize the unit size code. The programming
function must be repeated.)
FINISHED
If alarm is present, furnace
control will display error
code. If alarm is not present,
solid dash starts blinking on
7-segment LED display.
To enter Field Test
mode: Push and
hold button next
to 7-segment LED
display until solid
dash symbol appears. Release button.
Power-Up - Number displayed by integrated control represents unit size code (furnace
model and capacity). If three horizontal bars are displayed followed by continuous E203,
furnace control does not recognize unit size code. Congure per the following:
Yes No
Push and hold button. Integrated control
will display unit size code number for
each furnace model for three seconds.
Solid P starts blinking on
7-segment LED. P
P
Conguring Unit Size Codes

Page 16 31-5000724 Rev. 0
LED Diagnostic Codes
Code Diagnostic Codes / Status of Equipment Action Required to Clear and Recover
Idle mode (Decimal blinks at 1 Hertz - 0.5 seconds
ON, 0.5 seconds OFF).
A
Cubic feet per minute (cfm) setting for indoor blower
(1 second ON, 0.5 seconds OFF) / cfm setting for
current mode displayed.
C
Cooling stage (1 second ON, 0.5 seconds OFF) /
1 or 2 displayed / Pause / cfm setting displayed /
Pause / Repeat codes.
d
Dehumidication mode (1 second ON, 1 second
OFF) / cfm setting displayed / Pause / Repeat
codes.
h
Heat pump stage (1 second ON, 0.5 seconds OFF)
/ % of input rate displayed / Pause / cfm setting /
Pause / Repeat codes.
H
Gas Heat stage (1 second ON, 0.5 seconds OFF)
/ 1 or 2 displayed / Pause / cfm setting displayed /
Pause / Repeat codes. Blinking during ignition.
dF Defrost mode.
E110 Low line voltage. Line Voltage low (Voltage tower than nameplate rating).
Check power line voltage and correct. Alarm clears 5
seconds after fault recovered.
E113 High line voltage. Line Voltage high (Voltage higher than nameplate
rating). Provide power voltage within proper range.
System resumes normal operation 5 seconds after fault
recovered.
E114 Line voltage frequency out-of-range. No 60 Hertz power. Check voltage and line power
frequency. Correct voltage and frequency problems.
System resumes normal operation 5 seconds after fault
recovered.
E115 Low 24V - Control will restart if the error recovers. 24 Volt Power high (Range is 18 to 30 Volts). Check
and correct voltage. Check for additional power
robbing equipment connected to system. May require
installation of larger VA transformer to be installed in
furnace/air handler. Clears after fault recovered.
E125 Control failed self-check, internal error, failed
hardware. Will restart if error recovers, Integrated
control not communicating Covers hardware errors
(ame sense circuit faults, pin shorts, etc).
Hardware problem on the control. Cycle power on
control. Replace if problem prevents service and is
persistent. Cleared 300 seconds after fault recovered.
E126 Control internal communication problem. Hardware problem on the control. Cycle power on
control. Replace if problem prevents service and is
persistent. Cleared 300 seconds after fault recovered.
E200 Hard Lock out - Rollout circuit open or previously
open
Correct cause of rollout trip or replace ame rollout
switch. Test furnace operation. Cleared after fault
recovered.
E201 Indoor blower/communication failure - Unable to
communicate with blower motor
Indoor blower communication failure including power
outage. Lost communication with indoor blower motor.
Possible causes: motor not powered, loose wiring.
Problem may be on control or motor side. Cleared after
fault recovered.

Page 17
31-5000724 Rev. 0
Code Diagnostic Codes / Status of Equipment Action Required to Clear and Recover
E202 Indoor blower motor mismatch - indoor motor
horsepower does not match unit capacity
Incorrect appliance capacity code selected. Check for
proper conguring under Unit Size Code for Furnace/
Air Handler on conguration guide or in installation
instructions. Cleared after the correct match is detected
following a reset. (Remove thermostat from system
while applying power and reprogramming)
E203 Appliance capacity size is NOT programmed.
Invalid unit codes. Refer to conguration ow chart.
No appliance capacity code selected. Check for proper
conguring under Unit Size Codes for Furnace on
conguration guide or in installation instruction. Critical
Alert Cleared after valid unit code is read following a
reset (remove thermostat from system while applying
power and reprogramming)
E204 Gas valve mis-wired Check gas valve operation and wiring. Clears when
repaired
E205 Gas valve control relay contact shorted Check wiring on control and gas valve. If wiring is
correct replace control.
E207 Hot surface igniter sensed open - Refer to
troubleshooting
Measure resistance of hot surface igniter. Replace if
open or not within specied range found in installation/
operation manual. Resumes normal operation after fault
is cleared.
E223 Low pressure switch failed open Check pressure(inches W.C) of low pressure switch
closing on heat call. Measure operating pressure
(inches w.c.). Inspect vent and combustion air inducer
for correct operation and restriction. Resumes normal
operation after fault is cleared.
E224 Low pressure switch failed closed -Refer to
troubleshooting
Check pressure(inches W.C) of low pressure switch
closing on heat call. Measure operating pressure
(inches w.c.). Inspect vent and combustion air inducer
for correct operation and restriction. Resumes normal
operation after fault is cleared.
E225 High pressure switch failed open -Refer to
troubleshooting
Check pressure(inches W.C) of high pressure switch
closing on heat call. Measure operating pressure
(inches w.c. Inspect vent and combustion air inducer
for correct operation and restriction Resumes normal
operation after fault is cleared.
E226 High pressure switch failed closed -Refer to
troubleshooting
Check operation of high pressure closing on heat call.
Measure operating pressure (inches w.c.). Inspect vent
and combustion air inducer for correct operation and
restriction. Resumes normal operation after fault is
cleared.
E227 Low pressure switch open during trial for ignition or
run mode. Refer to troubleshooting
Check operation of low pressure switch closing on heat
call. Measure operating pressure (inches w.c.). Inspect
vent and combustion air inducer for correct operation
and restriction. Resumes normal operation after fault is
cleared.
E228 Combustion air inducer calibration failure Unable to perform pressure switch calibration. Check
vent system and pressure switch wiring connections.
Resumes normal operation after fault is cleared
E229 Ignition on high re IFC switched to high re ignition because low re
pressure switch did not close in allowed time. No action
is needed.

Page 18 31-5000724 Rev. 0
Code Diagnostic Codes / Status of Equipment Action Required to Clear and Recover
E240 Low ame current - Run mode- Refer to
troubleshooting
Check micro-amperes of ame sensor using control
diagnostics or eld installed mode. Clean or replace
sensor. Measure voltage of neutral to ground to ensure
good unit ground. Alert clears after current heat all has
been completed.
E241 Flame sensed out of sequence-Flame still present. Shut o󰀨 gas. Check for gas valve leak. Replace if
necessary. Alert clears when fault is recovered.
E250 Limit switch circuit open - Refer to troubleshooting. Check for proper ring rate on furnace. Ensure there
is no blockage in heater. Check for proper air ow. If
limit not closed within 3 minutes unit will go into 1 hour
soft lockout. Resumes normal operation after fault is
cleared.
E252 Discharge air temperature too high (gas heat only). Check temperature rise airow and input rate. Clear
when heat call is nished.
E270 Soft lockout - Exceeded maximum number of
retries. No ame current sensed.
Check for proper gas ow. Ensure that igniter is lighting
burners. Check ame sensor current. Clears when heat
call nishes successfully.
E271 Soft lockout - Exceeded maximum number of
retries. Last retry failed due to the pressure switch
opening.
Check pressure (inches w.c.) of low pressure switch
closing on heat call. Measure operating pressure
(inches w.c.). Inspect vent and combustion air inducer
for correct operation and restriction. Clears when heat
call nishes successfully.
E272 Soft lockout - Exceeded maximum number of
recycles. Last recycle due to the pressure switch
opening
Check operation of low pressure to see if it is stuck
closed on heat call. Check pressure (inches w.c.) of
high pressure switch closing on heat call. Measure
operating pressure. Inspect vent and combustion air
inducer for correct operation and restriction. Clears
when heat call nishes successfully.
E273 Soft lockout - Exceeded maximum number of
recycles. Last recycle due to ame failure
Check micro-amperes of ame sensor using control
diagnostics or eld installed mode. Clean or replace
sensor. Measure voltage of neutral to ground to ensure
good unit ground. Alert clears after current heat call has
been completed.
E274 Soft lockout - Exceeded maximum number of
recycles. Last recycle failed due to the limit circuit
opening or limit remained open longer than 3
minutes.
Shut down system 1-hour soft lockout. Check ring rate
and air ow. Check for blockage. Clears when heat call
nishes successfully.
E275 Soft lockout - Flame sensed out of sequence.
Flame signal is gone.
Shut o󰀨 gas. Check for gas valve leak. 1-hour soft
lockout. Clears when ame has been proven stable.
E276 Soft lockout calibration failure. Unable to perform pressure switch calibration. Check
vent system and pressure switch wiring connections.
1-hour soft lockout. Clears when calibration has nished
successfully.
E290 Ignitor circuit fault - Failed ignitor or triggering
circuitry.
Measure resistance of hot surface igniter. Replace if
open or not within specications. 1-hour soft lockout.
Clears when ame has been proven stable.
E291 Heat airow restricted below the minimum. Check for dirty lter and airow restriction. Check
blower performance. 1-hour soft lockout. Cleared when
heat call nishes successfully.

Page 19
31-5000724 Rev. 0
Code Diagnostic Codes / Status of Equipment Action Required to Clear and Recover
E292 Indoor blower motor unable to start due to
obstructed wheel seized bearings.
Indoor blower motor unable to start (seized bearing,
stuck wheel, etc.) Replace motor or wheel if assembly
does not operate or meet performance standards.
1-hour soft lockout. Clears after circulator successfully
starts.
E294 Combustion air inducer over current. Check combustion blower bearings wiring and
amps. Replace if does not operate or does not meet
performance standards. Clears after inducer current is
sensed to be in-range after the ignition following the soft
lockout or reset.
E295 Indoor blower motor temperature is too high. Indoor blower motor over temperature (motor tripped
on internal protector). Check motor bearings and amps.
Replace if necessary. Cleared after blower demand is
satised.
E310 Discharge error temperature sensor failure. Only
shown if shorted or out of range.
Compare discharge sensor resistance to temperature
resistance charts in installation instructions. Replace
sensor if necessary. Cleared after the current heat call
is completed.
E311 Heat rate reduced to match indoor blower airow. Warning Only. Furnace blower in cutback mode due to
restricted airow. Reduce ring rate every 60 seconds
to match available CFM. Check lter and duct system.
To clear replace lter if needed or repair/add duct.
2-stage controls will reduce ring rate to 1-stage. Clears
when heat call nished successfully.
E312 Restricted airow in cooling or continuous fan mode
is lower than CFM setting.
Warning Only. Restricted airow - Indoor blower is
running at a reduced CFM (Cutback Mode - The
variable speed motor has pre-set speed and torque
limiters to protect the motor from damage caused
by operating outside of design parameters (0 to 0.8"
W.C. total external static pressure). Check lter and
duct system. To clear, replace lter if needed or repair/
add duct. Cleared after the current service demand is
satised.
E347 No 24 Volt output on Y1 of "integrated control" with
outdoor unit.
Operation stopped. Y1 relay/Stage 1 failed. (Pilot relay
contacts did not close or the relay coil did not energize;
no input back to IFC chip.) Critical Alert. Cleared after
reset and Y1 input sensed.
E348 No 24 Volt output on Y2 of "integrated control" with
outdoor unit.
Y2 relay/Stage 2 failed. (Pilot relay contacts did not
close or the relay coil did not energize; no input back to
IFC chip.) Critical Alert. Cleared after reset and Y1 input
sensed.
E349 No 24 Volts between R & O on "integrated control"
with outdoor unit (dual fuel model required for heat
pump application).
Conguration link R to O needs to be restored. Replace
link or hardware. Critical Alert.

Page 20 31-5000724 Rev. 0
Operating Sequence System Demand System Response
System
Condition Step
Thermostat
Demand Relative Humidity
Compressor
Blower
CFM
(COOL)
Comments
1st
Stage O G Status D
NO CALL FOR DEHUMIDIFICATION
Normal Operation 1On On On Acceptable 24 VAC High 100%
Compressor and indoor
blower follow thermostat
demand
BASIC MODE (only active on a Y1 thermostat demand)
Normal Operation 1On On On Acceptable 24 VAC High 100% Thermostat energizes Y1
and de-energizes D on a
call for de-humidication
Dehumidication
Call 2On On On Demand 0 VAC High 70%
PRECISION MODE (operates independent of a Y1 thermostat demand)
Normal Operation 1On On On Acceptable 24 VAC High 100% Dehumidication mode
begins when humidity is
greater than set point.
Maximum overcool from
cooling setpoint is 2°F.
Dehumidication
Call 2On On On Demand 0 VAC High 70%
Dehumidication
Call ONLY 1On On On Demand 0 VAC High 70% Thermostat will keep
outdoor unit energized after
cooling temperature setpoint
has been reached in order
to maintain room humidity
setpoint. Maximum overcool
from cooling setpoint is 2°F.
• On-board links at indoor unit with a single stage outdoor unit
• With Condensing unit - Cut W914 (R to OS) on integrated control
• With Heat Pump - Cut W914 (R to DS) and W951 (R to O) on integrated control
Table 13. Cooling Operating Sequence
NF97DM and Single Stage Outdoor Unit