International comfort products N9MSE0261408A Installation instructions

Printed in U.S.A. 440 04 4402 06 8/11/2017
SERVICE AND TECHNICAL
SUPPORT MANUAL
Single Stage, PSC Blower Motor
35” Tall, High Efficiency Condensing Gas Furnace
N9MSE (A Series)
Save this manual for future reference.
Safety Labeling and Signal Words
DANGER, WARNING, CAUTION, and NOTE
The signal words DANGER, WARNING,
CAUTION,and NOTE are used to identify levels of
hazard seriousness. The signal word DANGER is
only used on product labels to signify an immediate
hazard. The signal words WARNING, CAUTION,
and NOTE will be used on product labels and
throughout this manual and other manual that may
apply to the product.
DANGER −Immediate hazards which will result in
severe personal injury or death.
WARNING −Hazards or unsafe practices which
could result in severe personal injury or death.
CAUTION −Hazards or unsafe practices which
may result in minor personal injury or product or
property damage.
NOTE −Used to highlight suggestions which will
result in enhanced installation, reliability, or
operation.
!WARNING
Signal Words in Manuals
The signal word CAUTION is used throughout
this manual in the following manner:
!CAUTION
Signal Words on Product Labeling
Signal words are used in combination with
colors and/or pictures or product labels.
The signal word WARNING is used throughout
this manual in the following manner:
Safety−alert symbol
When you see this symbol on the unit and in
instructions or manuals, be alert to the
potential for personal injury.
TABLE OF CONTENTS
START−UP CHECK SHEET 3...............................
START−UP, ADJUSTMENT, AND SAFETY CHECK 4...........
PRIME CONDENSATE TRAP WITH WATER 4.................
PURGE GAS LINES 4......................................
CHECK INLET GAS PRESSURE 6...........................
ADJUST MANIFOLD PRESSURE 6..........................
GAS RATE (CU FT./HR) 9...................................
ORIFICE SIZE AND MANIFOLD PRESSURE 10...............
ADJUST TEMPERATURE RISE 13............................
ADJUST BLOWER OFF DELAY 14............................
ADJUST COOLING AIRFLOW 14.............................
ADJUST THERMOSTAT HEAT ANTICIPATOR 14...............
CHECK SAFETY CONTROLS 14.............................
CHECKLIST 14.............................................
COOLING AIR DELIVERY 15.................................
SERVICE AND MAINTENANCE PROCEDURES 16.............
HEATING AND COOLING APPLICATION WIRING DIAGRAM 17..
RETRIEVING STORED FAULT CODES 17.....................
COMPONENT SELF−TEST 17...............................
CARE AND MAINTENANCE 18...............................
CLEANING AND/OR REPLACING AIR FILTER 18..............
BLOWER MOTOR AND WHEEL MAINTENANCE 18............
CLEANING BURNERS AND FLAME SENSOR 20...............
SERVICING HOT SURFACE IGNITER 21......................
FLUSHING COLLECTOR BOX AND DRAINAGE SYSTEM 21....
CLEANING CONDENSATE DRAIN AND TRAP 22..............
CLEANING HEAT EXCHANGERS 22..........................
WINTERIZATION 23........................................
SERVICE LABEL 24.........................................
WIRING DIAGRAM 25.......................................
TROUBLESHOOTING −FLOW CHART 26....................
SEQUENCE OF OPERATION 28.............................
PARTS REPLACEMENT INFORMATION GUIDE 29.............
PRODUCT NOMENCLATURE 30.............................
MODELS
N9MSE0261408A
N9MSE0401410A
N9MSE0401712A
N9MSE0601410A
N9MSE0601714A
N9MSE0801716A
N9MSE0802120A
N9MSE1002114A
N9MSE1002120A
N9MSE1202420A
N9MSE1402420A
Use of the AHRI Certified TM Mark indicates a
manufacturer’s participation in the program.
For verification of certification for individual
products, go to www.ahridirectory.org .

440 04 4402 06
Specifications are subject to change without notice.
2
SAFETY CONSIDERATIONS
Improper installation, adjustment, alteration, service,
maintenance, or use can cause explosion, fire, electrical shock,
or other conditions which may cause death, personal injury, or
property damage. Consult a qualified installer, service agency,
or your distributor or branch for information or assistance. The
qualified installer or agency must use factory−authorized kits or
accessories when modifying this product. Refer to the individual
instructions packaged with the kits or accessories when
installing.
Follow all safety codes. Wear safety glasses, protective clothing,
and work gloves. Use quenching cloth for brazing operations.
Have fire extinguisher available. Read these instructions
thoroughly and follow all warnings or cautions included in
literature and attached to the unit. Consult local building codes,
the current editions of the National Fuel Gas Code (NFCG)
NFPA 54/ANSI Z223.1, and the National Electrical Code (NEC)
NFPA 70.
In Canada refer to the current editions of the National standards
of Canada CAN/CSA−B149.1 and .2 Natural Gas and Propane
Installation Codes, and Canadian Electrical Code CSA C22.1.
Recognize safety information. This is the safety−alert symbol
. When you see this symbol on the unit and in instructions or
manuals, be alert to the potential for personal injury.
Understand these signal words; DANGER, WARNING, and
CAUTION. These words are used with the safety−alert symbol.
DANGER identifies the most serious hazards which will result in
severe personal injury or death. WARNING signifies hazards
which could result in personal injury or death. CAUTION is used
to identify unsafe practices which may result in minor personal
injury or product and property damage. NOTE is used to
highlight suggestions which will result in enhanced installation,
reliability, or operation.
!WARNING
PERSONAL INJURY, AND/OR PROPERTY
DAMAGE HAZARD
Failure to carefully read and follow this warning could
result in equipment malfunction, property damage,
personal injury and/or death.
Installation or repairs made by unqualified persons could
result in equipment malfunction, property damage,
personal injury and/or death.
The information contained in this manual is intended for
use by a qualified service technician familiar with safety
procedures and equipped with proper tools and test
instruments.
Installation must conform with local building codes and
with the Natural Fuel Gas Code (NFCG) NFPA 54/ANSI
Z223.1, and National standards of Canada
CAN/CSA−B149.1 and .2 Natural Gas and Propane
Installation Codes.
!WARNING
ELECTRICAL SHOCK HAZARD
Failure to follow this warning could cause personal
injury or death.
Before performing service or maintenance operations
on unit, always turn off main power switch to unit and
install lockout tag. Unit may have more than one power
switch.
!WARNING
CARBON MONOXIDE POISONING AND FIRE
HAZARD
Failure to follow safety warnings could result in personal
injury, death, and/or property damage.
This furnace is not designed for use in mobile homes,
trailers or recreational vehicles.
!CAUTION
CUT HAZARD
Failure to follow this caution may result in damage
personal injury.
Sheet metal parts may have sharp edges or burrs. Use
care and wear appropriate protective clothing, safety
glasses and gloves when handling parts and servicing
furnaces.

SERVICE AND TECHNICAL MANUAL Gas Furnace: N9MSE
440 04 4402 06 3
Specifications subject to change without notice.
START−UP CHECK SHEET
For PSC Models N9MSE
(This sheet is optional. Keep for future reference.)
Date of Start−Up:
Dealer Name:
Address:
City, State(Province), Zip or Postal Code:
Phone:
Owner Name:
Address:
City, State(Province), Zip or Postal Code:
Model Number:
Serial Number:
Setup Checks
Check the box when task is complete.
All Electrical Connections Tight?
Have hoses been relocated for furnace U/D/H application?
Condensate Drain Connected?
Condensate Drain Trapped?
Manual Gas Shut−off Upstream of Furnace/Drip Leg
Gas Valve turned ON?
Type of Gas: Natural: Propane: 
Filter Type and Size:
Check in box the Blower OFF Delay Jumper Heating Position
for Fan “Time OFF” Setting:
1 and 2 2 and 3 3 and 4 5 and 6
90 120 150 180
Calculated Input (BTU) Rate: (See Checks and Adjustments
Section).
Heating Check
Measured Line Pressure During Heat:
Measured Manifold Pressure: Heat
Temperature of Supply Air: Heat
Temperature of Return Air:
Temperature Rise (Supply −Return): Heat
In Rise Range (see furnace rating plate)?
Static Pressure (Ducts) High Heat: Supply
Return
The Blower Speed Tap used for: Heat
Optional Check: CO?
CO2?
Cooling Check
Temperature of Supply Air:
Temperature of Return Air:
Temperature Difference:
Static Pressure (Ducts) Cooling: Supply
Return
The Blower Speed Tap used for: Cooling
Dealer Comments:

SERVICE AND TECHNICAL SUPPORT MANUAL Gas Furnace: N9MSE
Specifications subject to change without notice.
4440 04 4402 06
START−UP, ADJUSTMENT, AND SAFETY
CHECK
NOTICE
IMPORTANT INSTALLATION AND START−UP
PROCEDURES
Failure to follow this procedure may result in a nuisance smoke
or odor complaint.
The manifold pressure, gas rate by meter clocking, temperature
rise and operation must be checked after installation. Minor
smoke and odor may be present temporarily after start−up from
the manufacturing process. Some occupants are more
sensitive to this minor smoke and odor. It is recommended that
doors and windows be open during the first heat cycle.
General
1. Furnace must have a 115-v power supply properly
connected and grounded.
NOTE: Proper polarity must be maintained for 115-v wiring.
Control status indicator light flashes rapidly and furnace does
not operate if polarity is incorrect or if the furnace is not
grounded.
2. Thermostat wire connections at terminals R, W, G, and Y
must be made at 24-v terminal block on furnace control.
3. Natural gas service pressure must not exceed 0.5 psig
(14-in. w.c., 1125 Pa), but must be no less than 0.16 psig
(4.5-in. w.c., 350 Pa).
4. Blower door must be in place to complete 115-v electrical
circuit and supply power to the furnace components.
UNIT OPERATION HAZARD
Failure to follow this caution may result in intermittent unit
operation or performance satisfaction.
These furnaces are equipped with a manual reset limit
switch in burner assembly. This switch opens and shuts off
power to the gas valve if an overheat condition (flame
rollout) occurs in the burner assembly/enclosure. Correct
inadequate combustion−air supply, improper gas pressure
setting, improper burner or gas orifice positioning, or
improper venting condition before resetting switch. DO
NOT jumper this switch.
CAUTION
!
Before operating furnace, check flame rollout manual reset
switch for continuity. If necessary, press button to reset switch.
EAC (115vac) terminal is energized whenever blower operates.
HUM (24vac) terminal is only energized the draft inducer is
energized in heating.
Prime Condensate Trap with Water
CARBON MONOXIDE POISONING HAZARD
Failure to follow these warnings could result in personal
injury or death.
Failure to use a properly configured trap or NOT
water-priming trap before operating furnace may allow
positive pressure vent gases to enter the structure through
drain tube. Vent gases contain carbon monoxide which is
tasteless and odorless.
!WARNING
1. Remove upper and middle collector box drain plugs
opposite of the condensate trap. (See Figure 1)
2. Connect field-supplied 5/8-in. (16 mm) ID tube with
attached funnel (see Figure 1) to upper collector box
drain connection.
3. Pour one quart (liter) of water into funnel/tube. Water
should run through collector box, overfill condensate
trap, and flow into open field drain.
4. Remove funnel; replace collector box drain plug.
5. Connect field-supplied 5/8-in. (16 mm) ID tube to middle
collector box drain port.
6. Pour one quart (liter) of water into funnel/tube. Water
should run through collector box, overfill condensate
trap, and flow into open field drain.
7. Remove funnel and tube from collector box and replace
collector box drain plug.
Figure 1 Priming Condensate Drain
L11F065
Representative drawing only, some models may vary in appearance.
Purge Gas Lines
If not previously done, purge the lines after all connections
have been made and check for leaks.
FIRE OR EXPLOSION HAZARD
Failure to follow this warning could result in personal injury,
death, and/or property damage.
Never purge a gas line into a combustion chamber. Never
test for gas leaks with an open flame. Use a commercially
available soap solution made specifically for the detection
of leaks to check all connections. A fire or explosion may
result causing property damage, personal injury or loss of
life.
!WARNING
Adjustments
FIRE HAZARD
Failure to follow this warning could result in personal injury,
death and/or property damage.
DO NOT bottom out gas valve regulator adjusting screw.
This can result in unregulated manifold pressure and result
in excess overfire and heat exchanger failures.
!WARNING

SERVICE AND TECHNICAL SUPPORT MANUAL Gas Furnace: N9MSE
Specifications subject to change without notice.
440 04 4402 06 5
FURNACE DAMAGE HAZARD
Failure to follow this caution may result in reduced furnace
life.
DO NOT redrill orifices. Improper drilling (burrs,
out−of−round holes, etc.) can cause excessive burner
noise and misdirection of burner flames. This can result in
flame impingement of heat exchangers, causing failures.
(See Figure 2)
CAUTION
!
FURNACE DAMAGE HAZARD
Failure to follow this caution may result in reduced furnace
life.
The 26,000 BTUH model has a lower nominal manifold
pressure than other models. Do not adjust the natural gas
manifold pressure above 1.8 in. w.c.
The 26,000 BTUH model can be identified by the green
label affixed to the solenoid of the gas valve.
Refer to the Adjustment section for setting the manifold
pressure.
USE Table 3 WHEN ADJUSTING 26,000 BTUH MODEL
MANIFOLD PRESSURE.
CAUTION
!
Figure 2 Orifice Hole
A93059
BURNER
ORIFICE
For proper operation and long term reliability the furnace input
rate must be within +/−2 percent of input rate on furnace rating
plate, or as adjusted for altitude.
The gas input rate on rating plate is for installation at altitudes
up to 2000 ft. (610 M).
NOTICE
The NATURAL GAS manifold pressure adjustments in Table 3
and Table 4 compensate for BOTH altitude AND gas heating
value. DO NOT apply an additional de−rate factor to the
pressures shown in Table 3 and Table 4. The values in this
Table and NOT referenced to sea level; they are
AS−MEASURED AT ALTITUDE.
The heating content of natural gas at altitude may already
provide for a reduction in capacity or altitude. Refer to Table 3.
No adjustments to the furnace may be necessary at altitude for
certain gas heating values.
Refer to the instructions provided in the factory-specified
Propane conversion kit for instructions for setting gas manifold
pressures for Propane applications.
NOTICE
The NATURAL GAS manifold pressure adjustments in Table 3
compensate for BOTH altitude AND gas heating value. DO
NOT apply an additional de−rate factor to the pressures shown
in Table 3. The values in this Table and NOT referenced to sea
level; they are AS−MEASURED AT ALTITUDE.
The heating content of natural gas at altitude may already
provide for a reduction in capacity or altitude. Refer to Table 3.
No adjustments to the furnace may be necessary at altitude for
certain gas heating values.
Refer to the instructions provided in the factory-specified
Propane conversion kit for instructions for setting gas manifold
pressures for Propane applications.
In the USA, the input rating for altitudes above 2000 ft. (610 M)
must be reduced by 2 percent for each 1000 ft. (305 M) above
sea level refer to Table 1. The natural gas manifold pressures
in Table 3 or Table 4 adjust for BOTH altitude and natural gas
heating value.
In Canada, the input rating must be reduced by 5 percent for
altitudes of 2000 ft. to 4500 ft. (610 to 1372 M) above sea level.
The natural gas manifold pressures in Table 3 or Table 4 adjust
for BOTH altitude and natural gas heating value.
NOTE: For Canadian altitudes of 2000 to 4500 ft. (610 to 1372
M), use USA altitudes of 2001 to 3000 ft. (611 to 914 M) in
Table 3 or Table 4.
To adjust manifold pressure to obtain the proper input rate, first,
determine if the furnace has the correct orifice installed. At
higher altitudes or different gas heat contents, it may be
necessary to change the factory orifice to a different orifice.
Tables have been provided in the furnace Service and
Technical Manual to match the required orifice to the manifold
pressure to the heat content and specific gravity of the gas. To
do this:
1. Obtain average yearly gas heat value (at installed
altitude) from local gas supplier.

SERVICE AND TECHNICAL SUPPORT MANUAL Gas Furnace: N9MSE
Specifications subject to change without notice.
6440 04 4402 06
2. Obtain average yearly gas specific gravity from local gas
supplier.
3. Find installation altitude range for your installation in the
manifold pressure tables in Table 3 or Table 4.
4. Find closest natural gas heat value and specific gravity in
Table 3 or Table 4. Follow heat value and specific
gravity lines to point of intersection to find orifice size and
low-and high-heat manifold pressure settings for proper
operation.
5. Check and verify burner orifice size in furnace. NEVER
ASSUME ORIFICE SIZE. ALWAYS CHECK AND
VERIFY.
NOTICE
If orifice hole appears damaged or it is suspected to have been
redrilled, check orifice hole with a numbered drill bit of correct
size. Never redrill an orifice. A burr−free and squarely aligned
orifice hole is essential for proper flame characteristics.
6. Replace orifice with correct size, if required by Table 3 or
Table 4. Use only factory−supplied orifices. See
EXAMPLE 1.
EXAMPLE 1:
0 - 2000 ft. (0 - 609.6M) altitude
Heating value = 1050 Btu/cu ft.
Specific gravity = 0.62
Therefore: Orifice No. 44
(Furnace is shipped with No. 44 orifices. In this example, all
main burner orifices are the correct size and do not need to be
changed to obtain proper input rate.)
Manifold pressure: 3.4-in. w.c. (847 Pa).
NOTE: To convert gas manifold Table pressures to Pascals,
multiply the in.w.c. value by 249.1 Pa/in. w.c. (1 in. wc. = 249.1
Pa).
Table 1 Altitude Derate Multiplier for USA
ALTITUDE
FT. (M)
PERCENT
OF DERATE
DERATE MULTIPLIER
FACTOR*
0–2000
(0−610) 0 1.00
2001–3000
(610−914) 4−6 0.95
3001–4000
(914−1219) 6−8 0.93
4001–5000
(1219−1524) 8−10 0.91
5001–6000
(1524−1829) 10−12 0.89
6001–7000
(1829−2134) 12−14 0.87
7001–8000
(2134−2438) 14−16 0.85
8001–9000
(2438−2743) 16−18 0.83
9001–10,000
(2743−3048) 18−20 0.81
* Derate multiplier factors are based on midpoint altitude for altitude range.
NOTE: For Canadian altitudes of 2000 to 4500 ft. (610 to
1372 M), use USA altitudes of 2001 to 3000 ft. (610 to 914
M)
Check Inlet Gas Pressure
The inlet gas pressure must be checked with the furnace
operating in maximum heat. This is necessary to make sure the
inlet gas pressure does not fall below the minimum pressure of
4.5 in. w.c.
1. Make sure the gas supply is turned off to the furnace and
at the electric switch on the gas valve.
2. Loosen set screw on inlet tower pressure tap no more
than one full turn with a 3/32−in. hex wrench or remove
the 1/8−in. NPT plug from the inlet pressure tap on the
gas valve.
3. Connect a manometer to the inlet pressure tap on gas
valve.
4. Turn on furnace power supply.
5. Turn gas supply manual shutoff valve to ON position.
6. Turn furnace gas valve switch to ON position.
7. Jumper R and W thermostat connections at the furnace
control board.
8. When main burners ignite, confirm inlet gas pressure is
between 4.5 in. w.c. (1125 Pa) and 13.6 in. w.c. (3388
Pa).
9. Remove jumper across thermostat connections to
terminate call for heat. Wait until the blower off delay is
completed.
10. Turn furnace gas valve electric switch to OFF position.
11. Turn gas supply manual shutoff valve to OFF position.
12. Turn off furnace power supply.
13. Remove manometer from the inlet pressure tap of the
gas valve.
FIRE HAZARD
Failure to follow this warning could result in personal injury,
death, and/or property damage.
Inlet pressure tap set screw must be tightened and 1/8−in.
NPT pipe plug must be installed to prevent gas leaks.
!WARNING
14. Tighten set screw on inlet tower pressure tap with
3/32−in. hex wrench, or if 1/8−in. NPT plug was
removed, apply pipe dope sparingly to end of plug and
re−install in the gas valve.
Adjust Manifold Pressure
NOTE: There are two manifold pressure tables in these
instructions. USE TABLE 3 FOR THE LOW CAPACITY 26,000
BTUH MODELS. The low capacity model can be identified by
the green label affixed to the top of the gas valve. For all other
models use Table 4.
1. Adjust manifold pressure to obtain proper gas input rate.
(See Figure 3)
a. Refer to the correct manifold pressure table for the
appropriate model.
b. Turn gas valve ON/OFF switch to OFF.
c. Loosen set screw on manifold tower pressure tap no
more than one full turn with a 3/32−in. hex wrench, or
remove the 1/8 inch NPT plug from the manifold
pressure tap on the gas valve. See Figure 3.
d. Connect a water column manometer or similar device
to manifold pressure tap.
e. Turn gas valve ON/OFF switch to ON.
f. Manually close blower door switch.
g. Jumper R and W thermostat connections on control
to start furnace. (See Figure 4)
h. Remove regulator adjustment cap from gas valve
pressure regulator and turn adjusting screw (3/16 or
smaller flat−tipped screwdriver) counterclockwise
(out) to decrease input rate or clockwise (in) to
increase input rate. (See Figure 3)

SERVICE AND TECHNICAL SUPPORT MANUAL Gas Furnace: N9MSE
Specifications subject to change without notice.
440 04 4402 06 7
NOTICE
For 40,000 BTUH to 120,000 BTUH models. DO NOT set
manifold pressure less than 2.8−in. w.c. (697 Pa) or more than
3.8−in. w.c. (947 Pa) for natural gas. If required manifold
pressure is outside this range, change main burner orifices to
obtain manifold pressure in this range.
FURNACE DAMAGE HAZARD
Failure to follow this caution may result in reduced furnace
life.
The 26,000 BTUH model has a lower nominal manifold
pressure than other models. Do not adjust the natural gas
manifold pressure above 1.8 in. w.c.
The 26,000 BTUH model can be identified by the green
label affixed to the solenoid of the gas valve.
Refer to the Adjustment section for setting the manifold
pressure.
USE TABLE 3 WHEN ADJUSTING 26,000 BTUH MODEL
MANIFOLD PRESSURE.
CAUTION
!
i. When correct input is obtained, replace cap that
conceal gas valve regulator adjustment screw. Main
burner flame should be clear blue, almost transparent
(See Figure 13)
j. Remove jumper R to W.
NOTE: Contact your HVAC distributor or gas supplier for metric
gas meter Tables, if required.
2. Verify natural gas input rate by clocking meter.
a. Turn off all other gas appliances and pilots served by
the meter.
b. Jumper R to W.
c. Run furnace for 3 minutes.
d. Measure time (in sec) for gas meter to complete 1
revolution and note reading. The 2 or 5 cubic feet dial
provides a more accurate measurement of gas flow.
e. Refer to Table 2 for cubic ft. of gas per hr.
Figure 3 Gas Valve (Single Stage) without
Tower Pressure Ports
ON/OFF Switch
Regulator Seal Cap
Regulator Adjustment
Regulator Seal Cap under Cap
1/2” NPT Outlet
1/8” NPT Manifold
Pressure Tap
1/8” NPT Inlet
Pressure Tap
1/2” NPT Inlet
A11153
Gas Valve (Single Stage) with Tower Pressure
Ports
ON/OFF SWITCH
1/8” NPT INLET
PRESSURE TAP
REGULATOR SEAL CAP
(REGULATOR ADJ.
UNDER CAP)
1/2” NPT
OUTLET
MANIFOLD PRESSURE TAP
SET SCREW: 3/32” HEX HEAD
ACCEPTS 5/16” HOSE CONNECTION
OUTP
INP
VENT
1/2” NPT
INLET
INLET PRESSURE
TAP SET SCREW:
3/32” HEX HEAD
ACCEPTS 5/16”
HOSE CONNECTION
Representative drawing only, some models may vary in appearance.
1/8” NPT
INLET PRESSURE TAP
1/2” NPT
INLET 1/2” NPT
OUTLET
Representative drawing only, some models may vary in appearance.
A170118
A170133
Low Capacity 26,000 BTUH Gas Valve without
Tower Pressure Ports
A170147
WhiteLabel Bl a c k T
ext
GreenLabel
Black T
ext
ON/OFF Switch
½” NPT Inlet
Regulator Seal Cap
Regulator Adjustment
Regulator Seal Cap
Under Cap
½” NPT Outlet
⅛” NPT Inlet
Pressure Tap
1.5” W.C.
White Rodgers
MODEL 36J60(515
24V 50/60HZ .280 AMPS
MAX. PRESS ½PSI
REG, 1.5” W.C.
Low Capacity 26,000 BTUH Gas Valve with Tower
Pressure Ports
A170140
1/8” NPT INLET
PRESSURE TAP
REGULATOR SEAL CAP
(REGULATOR ADJ.
UNDER CAP)
1/2” NPT
OUTLET
MANIFOLD PRESSURE TAP
SET SCREW: 3/32” HEX HEAD
ACCEPTS 5/16” HOSE CONNECTION
OUTP
INP
VENT
1/2” NPT
INLET
INLET PRESSURE
TAP SET SCREW:
3/32” HEX HEAD
ACCEPTS 5/16”
HOSE CONNECTION
Representative drawing only, some models may vary in appearance.
Green Label Black Text
ON/OFF
SWITCH
1.5”
W.C
.
White Label Black Text

SERVICE AND TECHNICAL SUPPORT MANUAL Gas Furnace: N9MSE
Specifications subject to change without notice.
8440 04 4402 06
f. Multiply gas rate cu ft./hr by heating value (Btuh/cu
ft.) to obtain input. If clocked rate does not match
required input from Step 1, increase manifold
pressure to increase input or decrease manifold
pressure to decrease input. Repeat steps b through e
until correct input is achieved. Re−install regulator
seal cap on gas valve.
g. If clocked rate does not match required input from
Step 1, increase manifold pressure to increase input
or decrease manifold pressure to decrease input.
Repeat steps b through e of Step 1 until correct heat
input is achieved. Re--install regulator seal cap on
gas valve.
3. Restore furnace to normal operating condition.
a. Turn gas valve ON/OFF switch to OFF.
b. Remove water column manometer or similar device
from manifold pressure tap.
c. Tighten set screw on manifold tower pressure tap
with 3/32−in. hex wrench, or if 1/8−in. NPT plug was
removed, apply pipe dope sparingly to end of plug
and reinstall in the gas valve.
d. Turn gas valve ON/OFF switch to ON.
e. Check for gas leaks and verify furnace operation
FIRE HAZARD
Failure to follow this warning could result in personal injury,
death, and/or property damage.
Manifold pressure tap set screw must be tightened and
1/8−in. NPT pipe plug must be installed to prevent gas
leaks.
!WARNING
Figure 4 Example of Single Stage Furnace Control for PSC Blower Motor
ÏÏÏ
ÏÏÏ
ÏÏÏ
ÏÏÏ
HEAT
OFF−DELAY COMPONENT TEST
TERMINAL
P1 −LOW VOLTAGE MAIN
HARNESS CONNECTOR
TRANSFORMER 24−VAC
CONNECTIONS
P2−HOT SURFACE IGNITOR (HSI) & INDUCER
MOTOR (IND) CONNECTOR
115 VAC
(L1) LINE
VOLTAGE
CONNECTION
SPARE1
COM/BLUE
115−VAC (L2) NEUTRAL
CONNECTIONS
24−V THERMOSTAT
TERMINALS
HUMIDIFIER TERMINAL
(24−VAC 0.5 AMP MAX)
3−AMP FUSE
LED OPERATION &
DIAGNOSTIC LIGHT
24VAC/RED
BLOWER SPEED
SELECTION TERMINALS
HUM
XFMR
HUMIDIFIER
TERMINAL
115−VAC
120 180
90 150
SPARE2
J2 JUMPER
J2
HUM
24VAC
BLW
SPARE1 SPARE2
L2
NEUTRAL
EAC 1 AMP
IND HSI
P2
L1
SPARE3
SPARE3
P1
1−AMP@115VAC
L13F013

SERVICE AND TECHNICAL SUPPORT MANUAL Gas Furnace: N9MSE
Specifications subject to change without notice.
440 04 4402 06 9
Table 2 Gas Rate (CU ft./hr)
SECONDS
FOR 1
REVOLUTION
SIZE OF TEST DIAL SECONDS
FOR 1
REVOLUTION
SIZE OF TEST DIAL
1 Cu Ft. 2 Cu Ft. 5 Cu Ft. 1 Cu Ft. 2 Cu Ft. 5 Cu Ft.
10 360 720 1800 55 65 131 327
11 327 655 1636 56 64 129 321
12 300 600 1500 57 63 126 316
13 277 555 1385 58 62 124 310
14 257 514 1286 59 61 122 305
15 240 480 1200 60 60 120 300
16 225 450 1125 62 58 116 290
17 212 424 1059 64 56 112 281
18 200 400 1000 66 54 109 273
19 189 379 947 68 53 106 265
20 180 360 900 70 51 103 257
21 171 343 857 72 50 100 250
22 164 327 818 74 48 97 243
23 157 313 783 76 47 95 237
24 150 300 750 78 46 92 231
25 144 288 720 80 45 90 225
26 138 277 692 82 44 88 220
27 133 267 667 84 43 86 214
28 129 257 643 86 42 84 209
29 124 248 621 88 41 82 205
30 120 240 600 90 40 80 200
31 116 232 581 92 39 78 196
32 113 225 563 94 38 76 192
33 109 218 545 96 38 75 188
34 106 212 529 98 37 74 184
35 103 206 514 100 36 72 180
36 100 200 500 102 35 71 178
37 97 195 486 104 35 69 173
38 95 189 474 106 34 68 170
39 92 185 462 108 33 67 167
40 90 180 450 110 33 65 164
41 88 176 439 112 32 64 161
42 86 172 429 116 31 62 155
43 84 167 419 120 30 60 150
44 82 164 409 124 29 58 145
45 80 160 400 129 28 56 140
46 78 157 391 133 27 54 135
47 76 153 383 138 26 52 130
48 75 150 375 144 25 50 125
49 73 147 367 150 24 48 120
50 72 144 360 157 23 46 115
51 71 141 355 164 22 44 110
52 69 138 346 171 21 42 105
53 68 136 340 180 20 40 100
54 67 133 333

SERVICE AND TECHNICAL SUPPORT MANUAL Gas Furnace: N9MSE
Specifications subject to change without notice.
10 440 04 4402 06
Table 3 Orifice Size and Manifold Pressure (in. w.c.) for Gas Input Rate −26,000 BTUH Single
Stage
A150571
AVG. GAS
HEAT VALUE
AT ALTITUDE Orifice Manifold Orifice Manifold Orifice Manifold Orifice Manifold
(Btu/cu ft) No. Pressure No. Pressure No. Pressure No. Pressure
900 44 1.8 43 1.7 43 1.7 43 1.8
0 925 44 1.7 44 1.8 43 1.6 43 1.7
(0) 950 44 1.6 44 1.7 44 1.8 44 1.8
975 44 1.6 44 1.6 44 1.7 44 1.7
to 1000 44 1.5 44 1.5 44 1.6 44 1.6
1025 44 1.4 44 1.5 44 1.5 44 1.6
2000 1050 44 1.3 44 1.4 44 1.4 44 1.5
(610) 1075 44 1.3 44 1.3 44 1.4 44 1.4
1100 44 1.2 44 1.3 44 1.3 44 1.4
U.S.A. 800 43 1.7 43 1.8 43 1.8 42 1.6
2001 (611) 825 43 1.6 43 1.7 43 1.7 43 1.8
to 850 44 1.8 44 1.8 43 1.6 43 1.7
3000 (914) 875 44 1.7 44 1.7 44 1.8 44 1.8
900 44 1.6 44 1.6 44 1.7 44 1.7
Canada 925 44 1.5 44 1.5 44 1.6 44 1.6
2001 (611) 950 44 1.4 44 1.5 44 1.5 44 1.6
to 975 44 1.3 44 1.4 44 1.4 44 1.5
4500 (1372) 1000 44 1.3 44 1.3 44 1.4 44 1.4
775 43 1.7 43 1.8 43 1.8 42 1.5
800 44 1.8 43 1.7 43 1.7 43 1.8
3001 825 44 1.7 44 1.8 44 1.8 43 1.7
(915) 850 44 1.6 44 1.7 44 1.7 44 1.8
875 44 1.5 44 1.6 44 1.6 44 1.7
900 44 1.4 44 1.5 44 1.5 44 1.6
4000 925 44 1.4 44 1.4 44 1.5 44 1.5
(1219) 950 44 1.3 44 1.3 44 1.4 44 1.4
750 43 1.7 43 1.7 43 1.8 43 1.8
775 44 1.8 43 1.6 43 1.7 43 1.7
4001 800 44 1.7 44 1.7 44 1.8 43 1.6
(1220) 825 44 1.6 44 1.6 44 1.7 44 1.8
850 44 1.5 44 1.5 44 1.6 44 1.7
to 875 44 1.4 44 1.5 44 1.5 44 1.6
5000 900 44 1.3 44 1.4 44 1.4 44 1.5
(1524) 925 44 1.3 44 1.3 44 1.4 44 1.4
725 43 1.7 43 1.7 43 1.8 43 1.8
5001 750 44 1.8 44 1.8 43 1.7 43 1.7
(1525) 775 44 1.7 44 1.7 44 1.8 44 1.8
800 44 1.6 44 1.6 44 1.7 44 1.7
825 44 1.5 44 1.5 44 1.6 44 1.6
850 44 1.4 44 1.4 44 1.5 44 1.5
6000 875 44 1.3 44 1.3 44 1.4 44 1.4
(1829) 900 44 1.2 44 1.3 44 1.3 44 1.4
675 43 1.8 43 1.8 42 1.5 42 1.6
6001 700 43 1.6 43 1.7 43 1.7 43 1.8
(1830) 725 44 1.7 44 1.8 43 1.6 43 1.7
750 44 1.6 44 1.7 44 1.7 44 1.8
775 44 1.5 44 1.6 44 1.6 44 1.7
7000 800 44 1.4 44 1.5 44 1.5 44 1.6
(2133) 825 44 1.3 44 1.4 44 1.4 44 1.5
850 44 1.3 44 1.3 44 1.4 44 1.4
* Orifice numbers shown in BOLD are factory-installed.
U.S.A. OnlyU.S.A. Only
to
U.S.A. Only
to
ORIFICE SIZE* AND MANIFOLD PRESSURE (IN WC) FOR GAS INPUT RATE
(
TABULATED DATA BASED ON 13,000 BTUH PER BURNER, DERATED 2%/1000 FT (305M) ABOVE SEA LEVE
L
ALTITUDE
RANGE
U.S.A. and CanadaU.S.A. and CanadaU.S.A. Only
ft (m)
SPECIFIC GRAVITY OF NATURAL GAS
0.58 0.60 0.62 0.64
to

SERVICE AND TECHNICAL SUPPORT MANUAL Gas Furnace: N9MSE
Specifications subject to change without notice.
440 04 4402 06 11
Table 3 (CONT.) Orifice Size and Manifold Pressure (in. w.c.) for Gas Input Rate −26,000 BTUH Single Stage
A150572
650 43 1.7 43 1.8 42 1.5 42 1.6
7001 675 44 1.8 43 1.7 43 1.7 43 1.8
(2134) 700 44 1.7 44 1.8 44 1.8 43 1.7
725 44 1.6 44 1.7 44 1.7 44 1.8
750 44 1.5 44 1.5 44 1.6 44 1.6
8000 775 44 1.4 44 1.4 44 1.5 44 1.5
(2438) 800 44 1.3 44 1.4 44 1.4 44 1.4
825 44 1.2 44 1.3 44 1.3 44 1.4
625 43 1.7 43 1.8 43 1.8 42 1.6
8001 650 44 1.8 43 1.7 43 1.7 43 1.8
(2439) 675 44 1.7 44 1.8 44 1.8 43 1.6
700 44 1.6 44 1.6 44 1.7 44 1.7
725 44 1.5 44 1.5 44 1.6 44 1.6
9000 750 44 1.4 44 1.4 44 1.5 44 1.5
(2743) 775 44 1.3 44 1.3 44 1.4 44 1.4
9001 600 43 1.7 43 1.8 43 1.8 42 1.6
(2744) 625 44 1.8 43 1.6 43 1.7 43 1.7
650 44 1.7 44 1.7 44 1.8 44 1.8
675 44 1.6 44 1.6 44 1.7 44 1.7
10000 700 44 1.4 44 1.5 44 1.5 44 1.6
(3048) 725 44 1.3 44 1.4 44 1.4 44 1.5
* Orifice numbers shown in BOLD are factory-installed.
U.S.A. Only
to
U.S.A. Only
to
U.S.A. Only
to
ORIFICE SIZE* AND MANIFOLD PRESSURE (IN WC) FOR GAS INPUT RATE
(
TABULATED DATA BASED ON 13,000 BTUH PER BURNER, DERATED 2%/1000 FT (305M) ABOVE SEA LEVE
L

SERVICE AND TECHNICAL SUPPORT MANUAL Gas Furnace: N9MSE
Specifications subject to change without notice.
12 440 04 4402 06
Table 4 Orifice Size and Manifold Pressure (in. w.c.) for Gas Input Rate −40,000 −140,000 BTUH
Single Stage
A11253A
SAGLARUTANFOYTIVARGCIFICEPSSAG.GVA
HEATVALUE0.580.600.620.64
AT ALTITUDE Orifice Manifold Orifice Manifold Orifice Manifold Orifice Manifold
(Btu/cu ft) No. Pressure No. Pressure No. Pressure No. Pressure
900 43 3.8 42 3.2 42 3.3 42 3.4
092543 3.6 43 3.7 43 3.8 42 3.2
(0) 950 43 3.4 43 3.5 43 3.6 43 3.7
975 44 3.7 44 3.8 43 3.4 43 3.6
to 1000 44 3.5 44 3.6 44 3.8 43 3.4
1025 44 3.3 44 3.5 44 3.6 44 3.7
2000 1050 44 3.2 44 3.3 44 3.4 44 3.5
(610) 1075 45 3.7 45 3.8 44 3.3 44 3.4
1100 46 3.7 46 3.8 45 3.8 44 3.2
U.S.A. 800 42 3.4 42 3.5 42 3.6 42 3.7
2001 (611) 825 43 3.8 42 3.3 42 3.4 42 3.5
to 850 43 3.6 43 3.7 42 3.2 42 3.3
3000 (914) 875 43 3.4 43 3.5 43 3.7 43 3.8
900 44 3.7 44 3.8 43 3.5 43 3.6
Canada 925 44 3.5 44 3.6 44 3.8 43 3.4
2001 (611) 950 44 3.3 44 3.4 44 3.6 44 3.7
to 975 44 3.2 44 3.3 44 3.4 44 3.5
4500 (1372) 1000 44 3.0 44 3.1 44 3.2 44 3.3
775 42 3.3 42 3.4 42 3.5 42 3.6
3001 800 43 3.8 42 3.2 42 3.3 42 3.4
(915) 825 43 3.6 43 3.7 43 3.8 42 3.2
850 44 3.8 43 3.5 43 3.6 43 3.7
875 44 3.6 44 3.7 43 3.4 43 3.5
4000 900 44 3.4 44 3.5 44 3.7 44 3.8
(1219) 925 44 3.2 44 3.4 44 3.5 44 3.6
950 44 3.1 44 3.2 44 3.3 44 3.4
750 42 3.3 42 3.4 42 3.5 42 3.6
4001 775 43 3.7 43 3.8 42 3.3 42 3.4
(1220) 800 43 3.5 43 3.6 43 3.7 43 3.8
825 44 3.8 43 3.4 43 3.5 43 3.6
850 44 3.5 44 3.7 44 3.8 43 3.4
5000 875 44 3.3 44 3.5 44 3.6 44 3.7
(1524) 900 44 3.2 44 3.3 44 3.4 44 3.5
925 44 3.0 44 3.1 44 3.2 44 3.3
725 42 3.2 42 3.3 42 3.4 42 3.5
5001 750 43 3.7 43 3.8 42 3.2 42 3.3
(1525) 775 43 3.4 43 3.5 43 3.7 43 3.8
800 44 3.7 44 3.8 43 3.4 43 3.5
825 44 3.5 44 3.6 44 3.7 44 3.8
6000 850 44 3.3 44 3.4 44 3.5 44 3.6
(1829) 875 44 3.1 44 3.2 44 3.3 44 3.4
900 44 2.9 44 3.0 44 3.1 44 3.2
675 42 3.4 42 3.5 42 3.6 42 3.8
6001 700 42 3.2 42 3.3 42 3.4 42 3.5
(1830) 725 43 3.6 43 3.7 43 3.8 42 3.3
750 43 3.4 43 3.5 43 3.6 43 3.7
775 44 3.6 44 3.7 43 3.4 43 3.5
7000 800 44 3.4 44 3.5 44 3.6 44 3.7
(2133) 825 44 3.2 44 3.3 44 3.4 44 3.5
850 44 3.0 44 3.1 44 3.2 44 3.3
to
to
to
to
ALTITUDE
RANGE
ft (m)
U.S.A. and Canada
SINGLE-STAGE FURNACE
(TABULATED DATA BASED ON 20,000 BTUH PER BURNER, DERATED 2%/1000 FT (305M) ABOVE SEA LEVEL)
U.S.A. Only
U.S.A. Only
U.S.A. Only U.S.A. Only U.S.A. and Canada

SERVICE AND TECHNICAL SUPPORT MANUAL Gas Furnace: N9MSE
Specifications subject to change without notice.
440 04 4402 06 13
Table 4 (CONT.) Orifice Size and Manifold Pressure (in. w.c.) for Gas Input Rate −40,000 −140,000 BTUH
Single Stage
A11253B
SAGLARUTANFOYTIVARGCIFICEPSSAG.GVA
HEATVALUE0.580.600.620.64
AT ALTITUDE Orifice Manifold Orifice Manifold Orifice Manifold Orifice Manifold
(Btu/cu ft) No. Pressure No. Pressure No. Pressure No. Pressure
ALTITUDE
RANGE
ft (m)
SINGLE-STAGE FURNACE
(TABULATED DATA BASED ON 20,000 BTUH PER BURNER, DERATED 2%/1000 FT (305M) ABOVE SEA LEVEL)
650 42 3.4 42 3.5 42 3.6 42 3.7
7001 675 43 3.8 42 3.2 42 3.3 42 3.4
(2134) 700 43 3.5 43 3.7 43 3.8 42 3.2
725 44 3.8 43 3.4 43 3.5 43 3.6
750 44 3.5 44 3.7 44 3.8 43 3.4
8000 775 44 3.3 44 3.4 44 3.5 44 3.7
(2438) 800 44 3.1 44 3.2 44 3.3 44 3.4
825 44 2.9 44 3.0 44 3.1 44 3.2
625 42 3.4 42 3.5 42 3.6 42 3.7
8001 650 43 3.8 42 3.2 42 3.3 42 3.4
(2439) 675 43 3.5 43 3.6 43 3.7 42 3.2
700 44 3.7 43 3.4 43 3.5 43 3.6
725 44 3.5 44 3.6 44 3.7 44 3.8
9000 750 44 3.3 44 3.4 44 3.5 44 3.6
(2743) 775 44 3.0 44 3.2 44 3.3 44 3.4
9001 600 42 3.3 42 3.4 42 3.6 42 3.7
(2744) 625 43 3.7 42 3.2 42 3.3 42 3.4
650 43 3.5 43 3.6 43 3.7 43 3.8
675 44 3.7 44 3.8 43 3.4 43 3.5
10000 700 44 3.4 44 3.5 44 3.7 44 3.8
(3048) 725 44 3.2 44 3.3 44 3.4 44 3.5
* Orifice numbers shown in BOLD are factory-installed.
to
to
to
U.S.A. Only U.S.A. OnlyU.S.A. Only
Adjust Temperature Rise
NOTE: Blower door must be installed when taking temperature
rise reading. Leaving blower door off will result in incorrect
temperature measurements, due to possible changes in duct
static pressure and airflow.
FURNACE DAMAGE HAZARD
Failure to follow this caution may result in:
SOverheating the heat exchangers or condensing
flue gases in heat exchanger areas not designed
for condensate
SShortened furnace life
SComponent damage
Temperature rise must be within limits specified on furnace
rating plate. Recommended operation is at midpoint of rise
range or slightly above.
CAUTION
!
Jumper R to W to check gas-heat temperature rise. Do not
exceed temperature rise ranges specified on unit rating plate.
This furnace must operate within the temperature rise ranges
specified on the furnace rating plate. Determine the air
temperature as follows:
1. Place duct thermometers in return and supply ducts as
close to furnace as possible. Be sure thermometers do
not “see” heat exchangers so that radiant heat does not
affect thermometer readings. This is particularly
important with straight−run ducts.
2. When thermometer readings stabilize, subtract return−air
temperature from supply−air temperature to determine
temperature rise.
If the temperature rise is outside this range, check the
following:
1. Gas input rate.
2. Derate for altitude if applicable.
3. Return and supply ducts for excessive restrictions
causing static pressures greater than 0.50−in. w.c. (125
Pa)
4. Adjust temperature rise by adjusting blower speed.
SIncrease blower speed to reduce temperature rise.
SDecrease blower speed to increase temperature rise.
ELECTRICAL OPERATION HAZARD
Failure to follow this warning could result in personal injury
or death.
Disconnect 115vac electrical power before changing speed
tap.
!WARNING
(Read following caution before changing taps.)
UNIT DAMAGE HAZARD
To avoid operating outside the rise range and avoid
component damage:
Refer to the Air Delivery Tables to determine which airflows
and settings are allowed for proper heating airflow. DO NOT
use the highlighted settings for heating airflow. The
highlighted settings are to be used for Cooling and
Continuous Fan ONLY.
CAUTION
!

SERVICE AND TECHNICAL SUPPORT MANUAL Gas Furnace: N9MSE
Specifications subject to change without notice.
14 440 04 4402 06
Change the blower speed taps as required to maintain proper
temperature rise for Heating and Cooling as described above.
To change blower motor speed selections for heating mode,
remove blower motor lead from control HEAT terminal(s). (See
Figure 4) Select desired blower motor speed lead(s) from the
other motor leads and relocate it/them to HEAT (heating blower
tap) terminal(s). Reconnect original lead on SPARE terminal.
Adjust Blower Off Delay (Heat Mode)
If desired, the main blower off time delay period may be
lengthened or shortened when operating in the heating mode
to provide greater comfort. For position and location of jumpers
on control center. (See Figure 4 and Figure 15)
The blower off-delay has four adjustable settings from 90 sec to
180 sec. (See Table 5) To change the blower off delay setting,
move the jumper from one set of pins on the control to the pins
used for the desired blower off delay. Factory blower off-delay
setting is 120 sec.
Table 5 Blower Off Delay Jumper Positions
PINS 1 AND 2 2 AND 3 3 AND 4 4 AND 5
Time (in sec.) 90 120 150 180
Adjust Cooling Airflow
The cooling airflow can be set from the remaining blower speed
taps. Refer to the Air Delivery Tables in these instructions.
FURNACE OVERHEATING HAZARD
Failure to follow this caution may result in reduced furnace
life.
Recheck temperature rise. It must be within limits specified
on the rating plate. Recommended operation is at the
mid-point of rise range or slightly above.
CAUTION
!
Adjust Thermostat Heat Anticipator
Mechanical thermostat: Set thermostat heat anticipator to
match the amp. draw of the electrical components in the R-W
circuit. Accurate amp. draw readings can be obtained at the
wires normally connected to thermostat sub-base terminals, R
and W. The thermostat anticipator should NOT be in the circuit
while measuring current.
1. Remove thermostat from sub-base or from wall.
2. Connect an amp. meter across the R and W sub-base
terminals or R and W wires at wall.
3. Record amp. draw across terminals when furnace is in
low heat and after blower starts.
4. Set heat anticipator on thermostat per thermostat
instructions and install on sub-base or wall.
5. Install blower access door.
Electronic thermostat: Set cycle rate for 3 cycles per hr.
Check Safety Controls
The flame sensor, gas valve, and pressure switch were all
checked in the Start−up procedure section as part of normal
operation.
1. Check Main Limit Switch
This control shuts off combustion system and energizes
air−circulating blower motor, if furnace overheats. By
using this method to check the temperature limit control,
it can be established that the limit is functioning properly
and that the limit will operate if there is a restricted
return−air supply or motor failure. If the limit control does
not function during this test, the cause must be
determined and corrected.
a. Run furnace for at least 5 minutes.
b. Gradually block off return air with a piece of
cardboard or sheet metal until the limit trips.
c. Unblock return air to permit normal circulation.
d. Burners will re−light when furnace cools down.
Figure 5 Amp. Draw Check with Ammeter
A96316
R Y W G
10 TURNS
THERMOSTAT SUBBASE
TERMINALS WITH
THERMOSTAT REMOVED
(ANITICIPATOR, CLOCK, ETC.,
MUST BE OUT OF CIRCUIT.)
HOOK-AROUND
AMMETER
EXAMPLE: 5.0 AMPS ON AMMETER
10 TURNS AROUND JAWS
= 0.5 AMPS FOR THERMOSTAT
ANTICIPATOR SETTING
FROM UNIT 24-V
CONTROL TERMINALS
2. Check Pressure Switch(es)
This control proves operation of the draft inducer blower.
a. Turn off 115−v power to furnace.
b. Disconnect inducer motor lead wires from wire
harness.
c. Turn on 115−v power to furnace.
d. Set thermostat to “call for heat” and wait 1 minute.
When low pressure switch is functioning properly, hot
surface igniter should NOT glow and control
diagnostic light flashes a status code 3. If hot surface
igniter glows when inducer motor is disconnected,
shut down furnace immediately.
e. Determine reason low pressure switch did not
function properly and correct condition.
f. Turn off 115−v power to furnace.
g. Reconnect inducer motor wires, replace door, and
turn on 115−v power.
h. Blower will run for 90 seconds before beginning the
call for heat again.
i. Furnace should ignite normally.
Checklist
1. Put away tools and instruments. Clean up debris.
2. Verify that the jumper is removed from the TEST/TWIN
terminal. Verify that there is nothing plugged into the PLT
connector.
NOTE: If there is a jumper connector plugged into PLT, remove
it and discard. (See Figure 4)
3. Verify that the Blower/Heat Off Delay jumpers are set as
desired. (See Figure 4 and Figure 15)
4. Verify that the blower (lower door in upflow position) and
control (“Main” or upper door in upflow position) doors
are properly installed.
5. Verify that the Status LED heartbeat (bright−dim). If not,
check that the power supply is energized and that the
blower door is secure. See Figure 14 to interpret
diagnostic codes.
6. Cycle test furnace with room thermostat to be sure that it
operates properly with the room thermostat. Check all
modes including Heat, Cool and Fan.
7. Check operation of accessories per manufacturer’s
instructions.
8. Review Home Owner’s Information with owner.
9. Attach entire literature packet to furnace.

SERVICE AND TECHNICAL SUPPORT MANUAL Gas Furnace: N9MSE
Specifications subject to change without notice.
440 04 4402 06 15
Table 6 COOLING AIR DELIVERY - CFM (With Filter 1)
UNIT
SIZE
RETURN-AIR
CONNECTION
SPEED
TAPS 2
EXTERNAL STATIC PRESSURE (in. w.c.)
0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
0261408 SIDE/BOTTOM
Black 989 938 880 824 766 498 631 568 494 413
Yellow 738 684 629 570 509 447 382 321 249 −7
Blue 660 606 542 484 425 363 306 242 −7−7
Red 494 421 366 305 240 −7−7−7−7−7
0401410 SIDE/BOTTOM
Black 1100 1055 1010 960 905 850 795 740 685 620
Yellow 955 915 875 830 790 740 695 645 590 530
Blue 820 795 765 730 695 655 615 570 515 460
Red 730 710 680 655 625 595 555 515 465 400
0401712 SIDE/BOTTOM
Black 1245 1195 1150 1100 1050 1000 945 890 830 775
Yellow 1165 1120 1075 1030 980 925 870 815 760 710
Orange 1045 1015 965 925 885 840 790 740 695 640
Blue 1000 960 930 890 850 810 765 715 665 615
Red 735 725 700 680 650 625 590 555 515 470
0601410 SIDE/BOTTOM
Black 1340 1295 1245 1190 1130 1065 1005 895 815 725
Yellow 1035 1010 980 945 910 865 795 730 665 605
Blue 845 825 810 785 755 710 670 625 570 515
Red 5770 750 730 710 675 640 600 560 510 455
0601714 SIDE/BOTTOM
Black 1665 1615 1550 1485 1420 1345 1270 1190 1105 985
Yellow 1340 1320 1295 1260 1215 1165 1110 1045 925 850
Orange 1050 1045 1035 1015 995 960 915 845 785 725
Blue 985 980 975 950 930 900 845 795 740 690
Red 5735 720 700 675 650 620 595 560 520 480
0801716 SIDE/BOTTOM
Black 1870 1810 1740 1670 1600 1525 1440 1355 1270 1180
Yellow 1525 1495 1460 1415 1365 1305 1240 1170 1090 990
Orange 1375 1355 1330 1300 1260 1210 1155 1090 1025 940
Blue 1045 1040 1030 1010 985 960 920 875 825 745
Red 5880 865 850 835 810 785 750 715 665 605
0802120 BOTTOM or
TWO-SIDES 3,4
Black 2360 2250 2160 2065 1970 1880 1785 1685 1580 1455
Yellow 2100 2030 1960 1885 1805 1720 1635 1545 1440 1305
Orange 1840 1810 1765 1725 1665 1590 1515 1430 1335 1240
Blue 1705 1685 1660 1615 1570 1510 1445 1370 1280 1135
Red 1425 1410 1385 1365 1335 1290 1245 1190 1120 1050
1002114 SIDE/BOTTOM
Black 1750 1705 1660 1605 1545 1475 1405 1305 1220 1140
Blue 1550 1510 1470 1430 1380 1320 1245 1170 1095 1015
Yellow 51290 1255 1220 1180 1130 1075 1020 960 885 800
Red 51085 1045 1010 960 915 865 805 740 665 595
1002120 BOTTOM or
TWO-SIDES 3,4
Black 2415 2330 2245 2155 2065 1965 1865 1760 1645 1530
Yellow 2130 2075 2010 1945 1865 1785 1695 1600 1490 1375
Orange 1830 1815 1785 1740 1685 1625 1550 1470 1370 1255
Blue 1690 1680 1655 1620 1580 1530 1465 1385 1295 1185
Red 1415 1405 1390 1370 1345 1305 1260 1200 1125 1050
1202420 BOTTOM or
TWO-SIDES 3,4
Black 2440 2360 2295 2215 2105 1975 1815 1710 1575 1405
Blue 2300 2245 2185 2090 2005 1855 1745 1635 1505 1370
Yellow 1805 1780 1750 1705 1650 1595 1515 1430 1330 1230
Orange 51560 1550 1535 1505 1470 1420 1360 1285 1205 1130
Red 51390 1385 1370 1345 1320 1285 1230 1175 1105 1035
1402420 BOTTOM or
TWO-SIDES 3,4
Black 2410 2325 2230 2135 2035 1930 1820 1700 1575 1445
Blue 2250 2175 2100 2020 1930 1825 1715 1600 1485 1370
Yellow 51740 1725 1700 1660 1610 1550 1470 1390 1295 1190
Orange 51500 1495 1485 1465 1435 1390 1335 1265 1185 1090
Red 51350 1345 1335 1315 1290 1255 1210 1150 1080 995
NOTE:
1. A filter is required for each return−air inlet. Airflow performance includes a 3/4 in. (19 mm) washable filter media such as contained in factory−authorized accessory
filter rack. See accessory list. To determine airflow performance without this filter, assume an additional 0.1 in. w.c. available external static pressure.
2. Blower speed taps are not always in the same order. Factory Default blower connections are as follows:
Heating airflow −BLUE (also used for Continuous Fan)
Cooling airflow −BLACK (enabled when the Y terminal is energized)
ADJUST THE BLOWER SPEED TAPS AS NECESSARY FOR THE PROPER AIR TEMPERATURE RISE FOR EACH INSTALLATION.
3. Airflows over 1800 CFM require bottom return, two−side return, or bottom and side return. A minimum filter size of 20” x 25” (508 x 635 mm) is required.
4. For upflow applications, air entering from one side into both the side of the furnace and a return air base counts as a side and bottom return.
5. Highlighted areas indicate that this airflow range is beyond the range allowed for heating. THESE AIRFLOW RANGES MAY ONLY BE USED FOR COOLING.
6. All airflow that are shown in BOLD exceed 0.58 Watts per CFM at the given external static pressure.
7. The “−” entry indicates an unstable operating conditiong.

SERVICE AND TECHNICAL SUPPORT MANUAL Gas Furnace: N9MSE
Specifications subject to change without notice.
16 440 04 4402 06
SERVICE AND MAINTENANCE
PROCEDURES
Untrained personnel can perform basic maintenance functions
such as cleaning and replacing air filters. All other operations
must be performed by trained service personnel. A qualified
service person should inspect the furnace once a year.
FIRE, INJURY OR DEATH HAZARD
Failure to follow this warning could result in personal
injury, death and/or property damage.
The ability to properly perform maintenance on this
equipment requires certain knowledge, mechanical
skills, tools, and equipment. If you do not possess
these, do not attempt to perform any service and
maintenance on this equipment other than those
procedures recommended in the Owner’s Manual.
!WARNING
ENVIRONMENTAL HAZARD
Failure to follow this caution may result in
environmental pollution.
Remove and recycle all components or materials (i.e.
oil, refrigerant, control board, etc.) before unit final
disposal.
CAUTION
!
ELECTRICAL SHOCK, FIRE OR EXPLOSION
HAZARD
Failure to follow this warning could result in personal
injury or death, or property damage.
Before installing, modifying, or servicing system, main
electrical disconnect switch must be in the OFF
position and install a lockout tag. There may be more
than one disconnect switch. Lock out and tag switch
with a suitable warning label. Verify proper operation
after servicing. Always reinstall access doors after
completing service and maintenance.
!WARNING
ELECTRICAL OPERATION HAZARD
Failure to follow this caution may result in improper
furnace operation or failure of furnace.
Label all wires prior to disconnection when servicing
controls. Wiring errors can cause improper and
dangerous operation.
CAUTION
!
Figure 6 Multipoise Orientations
A93041
General
These instructions are written as if the furnace is installed in an
upflow application. An upflow furnace application is where the
blower is located below the combustion and controls section of
the furnace, and conditioned air is discharged upward. Since
this furnace can be installed in any of the 4 positions shown in
Figure 6, you must revise your orientation to component
location accordingly.
Electrical Controls and Wiring
Pressure Switches
Each pressure switch is labeled with the reference location
(noted as “COLLECTOR BOX−LPS” or “HOUSING−HPS” ON
THE SWITCH). The nominal break point of each switch is
shown on the label below the reference location in inches of
water column, “W.C.” The maximum and minimum break point
of the switch is +/−0.05 inches of water column from the
nominal break point of the switch. The maximum make point of
the switch is 0.10 inches of water above the maximum break
point of the switch
Example: Nominal break point on pressure switch is 0.68−in.
W.C. The minimum break point of the switch is 0.63−in. W.C.
The maximum break point of the switch is 0.73−in. W.C. The
maximum make point of the switch is 0.83−in. W.C.
ELECTRICAL SHOCK HAZARD
Failure to follow this warning could result in personal injury
or death.
There may be more than one electrical supply to the
furnace. Check accessories and cooling unit for additional
electrical supplies that must be shut off during furnace
servicing. Lock out and tag switch with a suitable warning
label.
!WARNING
The electrical ground and polarity for 115−V wiring must be
properly maintained. Refer to Figure 7 for field wiring
information and to Figure 15 for furnace wiring information.
NOTE: If the polarity is not correct, the STATUS LED on the
control will flash code 10 and prevent the furnace from heating.
The control system also requires an earth ground for proper
operation of the control and flame−sensing electrode.
The 24−V circuit contains an automotive−type, 3−amp. fuse
located on the control. (See Figure 4) Any shorts of the 24−V
wiring during installation, service, or maintenance will cause
this fuse to blow. If fuse replacement is required, use ONLY a
3−amp. fuse. The control LED display will be off when fuse
needs to be replaced.
Troubleshooting
Refer to the service label. (See Figure 14—Service Label)
The Troubleshooting Guide −Flow Chart (See Figure 16) can
be a useful tool in isolating furnace operation problems.
Beginning with the word “Start,” answer each question and
follow the appropriate arrow to the next item.
The Guide −Flow Chart will help to identify the problem or
failed component. After replacing any component, verify correct
operation sequence.
Proper instrumentation is required to service electrical controls.
The control in this furnace is equipped with a Status Code LED
(Light−Emitting Diode) to aid in installation, servicing, and
troubleshooting. Status codes can be viewed at the indicator in
blower door. The green furnace control LED is either ON
heartbeat, off or a code composed of 1 or 2 digits. The first digit
is the number of short flashes, the second digit is the number of
long flashes.

SERVICE AND TECHNICAL SUPPORT MANUAL Gas Furnace: N9MSE
Specifications subject to change without notice.
440 04 4402 06 17
Figure 7 Heating and Cooling Application Wiring Diagram −Single−Stage Thermostat
115-V FIELD-
SUPPLIED
DISCONNECT
AUXILIARY
J-BOX
24-V
TERMINAL
BLOCK
THREE-WIRE
HEATING-ONLY
FIVE WIRE
NOTE 1
NOTE 2
FIELD-SUPPLIED
DISCONNECT
CONDENSING
UNIT
TWO
WIRE
FURNACE
C
O
N
T
R
O
L
R
G
COM
WCR GY
GND
GND
FIELD 24-V WIRING
FIELD 115-, 208/230-, 460-V WIRING
FACTORY 24-V WIRING
FACTORY 115-V WIRING
208/230- OR
460-V
THREE
PHASE
208/230-V
SINGLE
PHASE
BLOWER DOOR SWITCH
WHT
BLK
WHT
BLK
NOTES: Connect Y-terminal in furnace as shown for proper blower operation.
Some thermostats require a "C" terminal connection as shown.
If any of the original wire, as supplied, must be replaced, use
same type or equivalent wire.
W
Y
GND
THERMOSTAT
TERMINALS
1.
2.
3.
A11387
For an explanation of status codes, refer to service label
located on blower door or Figure 14, and the troubleshooting
guide which can be obtained from your distributor.
Retrieving Stored Fault Codes
NOTE: Fault codes cannot be retrieved if a thermostat signal
(24-V on W, Y, G, etc.) is present, or if any delays such as
blower off-delays are active.
The stored status codes will NOT be erased from the control
memory when 115- or 24-V power is interrupted. See the
Service Label (See Figure 14) for more information. The most
recent fault code may be retrieved as follows:
1. Leave 115-V power connected to furnace.
2. Observe the status LED through the blower door (the
lower door on upflow applications) indicator. Refer to the
Service Label (See Figure 14) to interpret the LED.
3. Remove the Main/Control door (the upper door on upflow
installations).
4. BRIEFLY disconnect and reconnect ONE of the main
limit wires.
5. The LED will flash the last stored fault code. Refer to the
Service Label (See Figure 14) to interpret the LED.
6. A component test sequence will follow.
7. Reinstall the Main/Control door.
Component Self−Test
NOTE: The furnace control component test allows all
components to run for a short time; except the gas valve and
humidifier terminal HUM 24 VAC are not energized. The EAC
terminal is energized when the blower is energized. The HUM
terminal is energized when the inducer is energized. This
feature helps diagnose a system problem in case of a
component failure. The component test feature will not operate
if any thermostat signal is present at the control and not until all
time delays are completed.
To begin Component Self−Test:
1. Remove blower access door.
2. Disconnect the thermostat R lead from furnace control.
3. Manually close blower door switch.
Caution must be taken when manually closing this switch for
service purposes.
ELECTRICAL SHOCK HAZARD
Failure to follow this warning could result in personal
injury, or death.
Blower access door switch opens 115−V power to
control. No component operation can occur unless
switch is closed. Caution must be taken when
manually closing this switch for service purposes.
!WARNING
4. For approximately 2 sec, short (jumper) the C terminal on
control to the TEST/TWIN 3/16—in. (5 mm)
quick-connect terminal on control until the LED goes off.
Remove jumper from terminals. (See Figure 4)
NOTE: If TEST/TWIN and C terminals are jumpered longer
than 2 sec, LED will flash code 10 and ignore component test
request.
Component test sequence is as follows:
a. LED will display previous status code 4 times.
b. Inducer motor starts and continues to run until Step f of
component test sequence.
c. After 7 seconds the hot surface igniter is energized for
15 sec., then off.
d. Blower motor operates on HEAT speed for 10 sec.
e. Blower motor operates on COOL speed for 10 sec.
f. Inducer motor stops.
5. Reconnect R lead to furnace control, remove tape from
blower door switch, and re-install blower door.
6. Verify furnace shut down by lowering thermostat setting
below room temperature.
7. Verify that furnace restarts by raising thermostat setting
above room temperature.

SERVICE AND TECHNICAL SUPPORT MANUAL Gas Furnace: N9MSE
Specifications subject to change without notice.
18 440 04 4402 06
Care and Maintenance
FIRE OR EXPLOSION HAZARD
Failure to follow this warning could result in personal
injury, death and/or property damage.
Never store flammable or combustible materials on,
near, or in contact with the furnace, such as:
1. Spray or aerosol cans, rags, brooms, dust
mops, vacuum cleaners, or other cleaning
tools.
2. Soap powders, bleaches, waxes or other
cleaning compounds, plastic or plastic
containers, gasoline, kerosene, cigarette lighter
fluid, dry cleaning fluids, or other volatile fluids.
3. Paint thinners and other painting compounds,
paper bags, or other paper products. Exposure
to these materials could lead to corrosion of the
heat exchangers.
!WARNING
For continuing high performance and to minimize possible
furnace failure, periodic maintenance must be performed on
this furnace. Consult your local dealer about proper frequency
of maintenance and the availability of a maintenance contract.
ELECTRICAL SHOCK AND FIRE HAZARD
Failure to follow this warning could result in personal
injury, death, and/or property damage.
Turn off the gas and electrical supplies to the furnace
and install lockout tag before performing any
maintenance or service. Follow the operating
instructions on the label attached to the furnace.
!WARNING
CARBON MONOXIDE POISONING AND FIRE
HAZARD
Failure to follow this warning could result in personal
injury, death and/or property damage.
Never operate furnace without a filter or filtration
device installed. Never operate a furnace with filter or
filtration device access doors removed.
!WARNING
CUT HAZARD
Failure to follow this caution may result in personal
injury.
Sheet metal parts may have sharp edges or burrs.
Use care and wear appropriate protective clothing,
safety glasses and gloves when handling parts, and
servicing furnaces.
CAUTION
!
The minimum maintenance on this furnace is as follows:
1. Check and clean air filter each month or more frequently
if required. Replace if torn.
2. Check blower motor and wheel for cleanliness each
heating and cooling season. Clean as necessary.
3. Check electrical connections for tightness and controls
for proper operation each heating season. Service as
necessary.
4. Inspect burner compartment before each heating season
for rust, corrosion, soot or excessive dust. If necessary,
have furnace and burner serviced by a qualified service
agency.
5. Inspect the vent pipe/vent system before each heating
season for water leakage, sagging pipes or broken
fittings. Have vent pipes/vent system serviced by a
qualified service agency.
6. Inspect any accessories attached to the furnace such as
a humidifier or electronic air cleaner. Perform any service
or maintenance to the accessories as recommended in
the accessory instructions.
Cleaning and/or Replacing Air Filter
The air filter type may vary depending on the application or
orientation. The filter is external to the furnace casing. There
are no provisions for an internal filter with this furnace. See
“Filter Arrangement” under the “Installation” section of this
manual.
NOTE: If the filter has an airflow direction arrow, the arrow
must point toward the blower.
To clean or replace filters, proceed as follows:
ELECTRICAL SHOCK, FIRE OR EXPLOSION
HAZARD
Failure to follow this warning could result in personal
injury or death, or property damage.
Before installing, modifying, or servicing system, main
electrical disconnect switch must be in the OFF
position and install a lockout tag. There may be more
than one disconnect switch. Lock out and tag switch
with a suitable warning label. Verify proper operation
after servicing. Always reinstall access doors after
completing service and maintenance.
!WARNING
1. Turn off electrical supply to furnace.
2. Remove filter cabinet door.
3. Slide filter out of cabinet.
4. If equipped with permanent, washable filter, clean filter by
spraying cold tap water through filter in opposite direction
of airflow. Rinse filter and let dry. Oiling or coating of the
filter is not recommended.
5. If equipped with factory specified disposable media filter,
replace only with a factory specified media filter of the
same size.
6. Slide filter into cabinet.
7. Replace filter cabinet door.
8. Turn on electrical supply to furnace.
Blower Motor and Wheel Maintenance
To ensure long life, economy, and high efficiency, clean
accumulated dirt and grease from blower wheel and motor
annually.
The inducer and blower motors are pre−lubricated and require
no additional lubrication. These motors can be identified by the
absence of oil ports on each end of the motor.
The following items should be performed by a qualified service
technician. Clean blower motor and wheel as follows:
1. Turn off electrical supply to furnace.

SERVICE AND TECHNICAL SUPPORT MANUAL Gas Furnace: N9MSE
Specifications subject to change without notice.
440 04 4402 06 19
2. Remove blower door.
3. All factory wires can be left connected, but field
thermostat and accessory wiring may need to be
disconnected depending on their length and routing.
4. If the vent and combustion air pipe passes through the
blower compartment, it will be necessary to remove the
pipes from the blower compartment.
Disconnect the vent and combustion air pipe by:
a. Loosen the clamps on the vent couplings and
combustion air pipe external to the furnace.
b. Separate the pipes from the couplings and move
them aside.
c. Loosen the clamps on the vent couplings and
combustion air pipe located on the blower shelf.
d. Separate the pipes from the blower compartment and
set aside.
e. Remove the couplings from the pipe adapters and set
aside.
f. After servicing the blower, reverse steps a through e.
g. Tighten all clamps 15 lb−in.
See Figure 8 for steps 5 through 14.
5. Remove screws securing blower assembly to blower
shelf and slide blower assembly out of furnace. Detach
ground wire and disconnect blower motor harness plugs
from blower motor.
NOTE: Blower wheel is fragile. Use care.
6. Clean blower wheel and motor by using a vacuum with
soft brush attachment. Be careful not to disturb balance
weights (clips) on blower wheel vanes. Do not bend
wheel or blades as balance will be affected.
7. If greasy residue is present on blower wheel, remove
wheel from the blower housing and wash it with an
appropriate degreaser. To remove wheel:
a. Mark blower wheel location on shaft before
disassembly to ensure proper reassembly.
b. Loosen setscrew holding blower wheel on motor
shaft.
NOTE: Mark blower mounting arms and blower housing so
each arm is positioned at the same hole location during
reassembly.
c. Mark blower wheel orientation and cutoff plate
location to ensure proper reassembly.
d. Remove screws securing cutoff plate and remove
cutoff plate from housing.
e. Remove bolts holding motor mounts to blower
housing and slide motor and mounts out of housing.
f. Remove blower wheel from housing.
g. Clean wheel per instructions on degreaser cleaner.
Do not get degreaser in motor.
8. Reassemble motor and blower wheel by reversing items
7b through 7f. Ensure wheel is positioned for proper
rotation.
9. Torque motor mounting bolts to 40 +/−10 lb−in. when
reassembling.
10. Torque blower wheel set screw to 160 +/−20 lb−in. when
reassembling.
11. Verify that blower wheel is centered in blower housing
and set screw contacts the flat portion of the motor shaft.
Loosen set screw on blower wheel and reposition if
necessary.
12. Spin the blower wheel by hand to verify that the wheel
does not rub on the housing.
13. Reinstall blower assembly in furnace.
Figure 8 Blower Assembly
A11584A
SET SCREW
MOTOR WHEEL HUB
MOTOR SHAFT FLAT
A11584B
SCREW
MOTOR ARM
GROMMET
A11584C
SCREW LOCATION
BLO HSG ASSY
BRACKET
BRACKET
ENGAGEMENT
DETAIL A
A11584D
SEE DETAIL A
BRACKET
SCREW
(GND)
BLOWER HSG ASSY
MOTOR, BLOWE
R
WHEEL, BLOWER
CUTOFF, BLOWER
A11584E
POWER CHOKE
OR CAPACITOR
WHEN REQUIRED

SERVICE AND TECHNICAL SUPPORT MANUAL Gas Furnace: N9MSE
Specifications subject to change without notice.
20 440 04 4402 06
14. Reinstall 2 screws securing blower assembly to blower
deck.
15. Reconnect blower leads to furnace control. Refer to
furnace wiring diagram, and connect thermostat leads if
previously disconnected.
NOTE: Be sure to attach ground wire and reconnect blower
harness plugs to blower motor.
ELECTRICAL OPERATION HAZARD
Failure to follow this warning could result in personal
injury or death.
Blower door switch opens 115−V power to control. No
component operation can occur unless switch is closed.
Caution must be taken when manually closing this
switch for service purposes.
!WARNING
16. Downflow or horizontal furnaces with vent pipe through
furnace only:
a. Install and connect short piece of vent pipe inside
furnace to existing vent.
b. Connect vent connector to vent elbow.
17. Turn on electrical supply. Manually close blower door
switch. Use a piece of tape to hold switch closed. Check
for proper rotation and speed changes between heating
and cooling by jumpering R to G and R to Y on furnace
control thermostat terminals. If outdoor temperature is
below 70_F (21_C), turn off circuit breaker to outdoor unit
before running furnace in the cooling cycle. Turn outdoor
circuit breaker on after completing cooling cycle. (See
Figure 4)
NOTE: If R−W/W1 thermostat terminals are jumpered at the
time blower door switch is closed, blower will run for 90 sec
before beginning a heating cycle.
a. Perform component self−test as shown at the bottom
of the SERVICE label, located on the blower door.
b. Verify blower is rotating in the correct direction
18. If furnace is operating properly, RELEASE BLOWER
DOOR SWITCH. Remove any jumpers or reconnect any
disconnected thermostat leads. Replace blower door.
19. Turn on gas supply and cycle furnace through one
complete heating cycle. Verify the furnace temperature
rise as shown in Adjustments Section. Adjust
temperature rise as shown in Adjustments Section.
Cleaning Burners and Flame Sensor
The following items must be performed by a qualified service
technician. If the burners develop an accumulation of light dirt
or dust, they may be cleaned by using the following procedure:
NOTE: Use a back-up wrench on the gas valve to prevent the
valve from rotating on the manifold or damaging the mounting
to the burner assembly.
ELECTRICAL SHOCK AND FIRE HAZARD
Failure to follow this warning could result in personal
injury, death, and/or property damage.
Turn off the gas and electrical supplies to the furnace
and install lockout tag before performing any
maintenance or service. Follow the operating
instructions on the label attached to the furnace.
!WARNING
Refer to Figure 9.
1. Disconnect power at external disconnect, fuse or circuit
breaker.
2. Turn off gas at external shut-off or gas meter.
3. Remove control door and set aside.
4. Turn electric switch on gas valve to OFF.
5. Disconnect the gas pipe from gas valve and remove pipe
from the furnace casing.
6. Remove individual wires from terminals on gas valve.
7. Disconnect Hot Surface Igniter (HSI) wires from HSI.
8. Disconnect Flame Sensor wire from Flame Sensor.
9. Support the manifold and remove the 4 screws that
secure the manifold assembly to the burner assembly
and set aside. Note the location of the green/yellow wire
and ground terminal.
10. Inspect the orifices in the manifold assembly for
blockages or obstructions. Remove orifice and clean or
replace orifice.
11. Remove the four screws that attach the top plate of the
casing to the furnace.
12. Raise top plate up slightly and prop it up with a small
piece of wood or folded cardboard.
13. Support the burner assembly and remove the screws
that attach the burner assembly to the heat exchanger
cell panel.
14. Remove wires from both rollout switches.
15. Slide one−piece burner out of slots on sides of burner
assembly.
16. Remove the flame sensor from the burner assembly.
17. (Optional) Remove the Hot Surface Igniter (HSI) and
bracket from the burner assembly.
18. Check igniter resistance. Nominal resistance is 40 to 70
ohms at room temperature and is stable over the life of
the igniter.
19. Clean burner with a brush and a vacuum.
20. Clean the flame sensor with fine steel wool (0000 grade).
Do not use sand paper or emery cloth.
Figure 9 Burner Assembly
BURNER ASSY
FLAME SENSOR
(BELOW BURNER)
FLAME ROLL−OUT SWITCH
BURNER SUPT. ASSY
L11F064
Representative drawing only, some models may vary in appearance.
To reinstall burner assembly:
1. Install the Hot Surface Igniter (HSI) and bracket in burner
assembly.
2. Install flame sensor on burner.
3. Align the edges of the one-piece burner with the slots in
the burner assembly and slide the burners forward until
they are fully seated in the burner assembly.
4. Align the orifices in the manifold assembly with the
support rings on the end of the burner.