SERVICE AND TECHNICAL SUPPORT MANUAL
Gas Furnace: N9MSB
Specifications subject to change without notice.
12
440 04 4411 03
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
3. Verify that the Blower/Heat Off Delay jumpers are set as
desired. (See
and
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 glows. If not, check that the
power supply is energized and that the blower door is
secure. See
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.
Table 5
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
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
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
5
770
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
5
735
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
5
880
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
1290
1255
1220
1180
1130
1075
1020
960
885
800
Red
5
1085
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
5
1560
1550
1535
1505
1470
1420
1360
1285
1205
1130
Red
5
1390
1385
1370
1345
1320
1285
1230
1175
1105
1035
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.
