Allied A98USMV User manual

508420-01 Issue 2345 Page 1 of 75
SERVICE MANUAL
A98USMV Gas Furnace
(P) 508420-01
*P508420-01*
Table of Contents
Technical Specications - A98USMV...........................2
Parts Arrangement.......................................................7
Unit Components.........................................................8
Conguring Unit Size Codes .....................................16
Comfort Sync Wi-Fi® Thermostat (if applicable) ........31
Placement and Installation ........................................36
Joint Cementing Procedure.......................................37
Venting Practices.......................................................38
Vent Piping Guidelines ..............................................40
Condensate Piping ....................................................50
Start-Up .....................................................................55
Heating System Service Checks ...............................56
Typical Operating Characteristics..............................60
Maintenance..............................................................61
Wiring and Sequence of Operation ...........................64
Field Wiring Applications with Conventional Thermostat
...................................................................................67
Sequence of Operation and Troubleshooting Flow Chart
...................................................................................70
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
A98USMV 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. A98USMV units are available in heating
capacities from 66,000 to 132,000 Btuh (19.3 to 38.6 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. A98USMV
models include a variable capacity integrated control that
can be used with Allied Air Comfort Sync Wi-Fi® thermostat
as part of a communicating comfort system. All A98USMV
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.

508420-01Issue 2345Page 2 of 75
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.)
UPFLOW / HORIZONTAL
A98USMV070B12S 66,000 64,000 98.0% 3 Tons 1/2 120-60-1 15 7.7 40 132
A98USMV090C12S 88,000 85,000 98.0% 3 Tons 1/2 120-60-1 15 7.7 40 146
A98USMV090C16S 88,000 85,000 98.0% 4 Tons 1/2 120-60-1 15 10.1 40 153
A98USMV090C20S 88,000 85,000 98.0% 5 Tons 1/2 120-60-1 20 12.8 40 156
A98USMV110C20S 110,000 106,000 98.0% 5 Tons 1/2 120-60-1 20 12.8 40 164
A98USMV135D20S 132,000 127,000 98.0% 5 Tons 1/2 120-60-1 20 12.8 40 179
Note: For vent length and clearances to combustibles, please reference installation instructions.
* At full capacity
Technical Specications - A98USMV
MODEL NUMBER GUIDE
Numeric Code
S = Stainless Steel Heat Exchanger
8 = 3 Ton add on cooling
12 = 3 Ton add on cooling
16 = 4 Ton add on cooling
20 = 5 Ton add on cooling
B = 17.5 Width
C = 21.0 Width
D = 24.5 Width
A = Flagship
98 = 98% Efficiency
U = Upflow/Horizontal
D = Downflow
S = Communicating-Enabled
M = Modulation
V = Variable Speed
Heating Input x 1000
A 98 U S M V 110 C 20 S - 01

508420-01 Issue 2345 Page 3 of 75
BLOWER PERFORMANCE: BOTTOM 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
UPFLOW / HORIZONTAL
A98USMV070B12S
1/2
HP 10 x 9
50 -
80
Max.
Input
+15% 538 833 1128
2nd
Stage
+10% 862 1063 1218 1369
+7.5% 496 772 1048 Default 810 962 1130 1269
Default 453 710 967 -10% 707 841 1007 1140
35 -
65
Min.
Input
1st
Stage
+10% 604 740 843 971
-7.5% 419 657 895 Default 558 668 770 855
-15% 385 604 822 -10% 504 603 683 793
A98USMV090C12S
1/2
HP 10 x 9
60 - 90
Max.
Input
+15% 734 1014 1295
2nd
Stage
+10% 879 1040 1212 1362
+7.5% 697 953 1209 Default 803 946 1104 1246
Default 660 891 1122 -10% 721 842 972 1117
35 - 65
Min.
Input
1st
Stage
+10% 626 710 832 952
-7.5% 616 828 1041 Default 569 672 764 862
-15% 572 766 959 -10% 524 612 687 785
A98USMV090C16S
3/4
HP 11 x 11
50 - 80
Max.
Input
+15% 835 1234 1633
2nd
Stage
+10% 1168 1379 1583 1771
+7.5% 776 1155 1534 Default 1079 1267 1444 1645
Default 716 1075 1434 -10% 938 1148 1324 1469
35 -
65
Min.
Input
1st
Stage
+10% 843 1007 1159 1315
-7.5% 652 997 1342 Default 780 915 1047 1190
-15% 589 919 1249 -10% 693 838 959 1070
A98USMV090C20S
1 HP 11 x 11
50 - 80
Max.
Input
+15% 665 1159 1653
2nd
Stage
+10% 1385 1593 1818 2019
+7.5% 618 1085 1553 Default 1226 1463 1647 1884
Default 571 1012 1453 -10% 1063 1320 1504 1675
35 - 65
Min.
Input
1st
Stage
+10% 933 1054 1274 1466
-7.5% 507 917 1328 Default 836 978 1121 1336
-15% 443 823 1203 -10% 740 868 1010 1152
A98USMV110C20S
1 HP 11 x 11
50 -
80
Max.
Input
+15% 861 1424 1988
2nd
Stage
+10% 1312 1560 1744 1955
+7.5% 825 1349 1874 Default 1219 1405 1569 1796
Default 789 1274 1759 -10% 1075 1272 1428 1634
35 -
65
Min.
Input
1st
Stage
+10% 937 1064 1247 1407
-7.5% 731 1187 1644 Default 864 972 1146 1282
-15% 673 1101 1528 -10% 790 888 1025 1167
A98USMV135D20S
1 HP 11 x 11
55 -
85
Max.
Input
+15% 1033 1534 2035
2nd
Stage
+10% 1353 1567 1751 1994
+7.5% 957 1426 1895 Default 1202 1448 1616 1828
Default 881 1317 1754 -10% 1080 1290 1472 1668
35 -
65
Min.
Input
1st
Stage
+10% 935 1074 1260 1450
-7.5% 817 1235 1652 Default 834 983 1116 1306
-15% 753 1152 1550 -10% 732 867 1023 1145
** See installation instructions for proper blower setup

508420-01Issue 2345Page 4 of 75
BLOWER PERFORMANCE: SIDE 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
UPFLOW / HORIZONTAL
A98USMV070B12S
1/2 HP 10 x 9
50 - 80
Max.
Input
+15% 531 812 1093
2nd
Stage
+10% 840 1054 1208 1357
+7.5% 490 756 1022 Default 752 946 1130 1231
Default 449 700 951 -10% 688 805 991 1114
35 - 65
Min.
Input
1st
Stage
+10% 593 706 805 959
-7.5% 413 635 857 Default 543 642 729 824
-15% 378 571 763 -10% 503 584 665 720
A98USMV090C12S
1/2 HP 10 x 9
60 - 90
Max.
Input
+15% 702 971 1240
2nd
Stage
+10% 843 1017 1168 1300
+7.5% 673 926 1178 Default 772 912 1054 1193
Default 644 880 1116 -10% 698 799 946 1111
35 - 65
Min.
Input
1st
Stage
+10% 610 707 797 921
-7.5% 608 814 1020 Default 561 643 718 811
-15% 571 747 923 -10% 526 605 667 729
A98USMV090C16S
3/4 HP 11 x 11
50 - 80
Max.
Input
+15% 812 1204 1595
2nd
Stage
+10% 1140 1341 1526 1728
+7.5% 759 1127 1495 Default 1043 1235 1398 1566
Default 706 1051 1395 -10% 913 1124 1279 1402
35 - 65
Min.
Input
1st
Stage
+10% 823 1009 1135 1292
-7.5% 608 814 1020 Default 758 882 1026 1151
-15% 571 747 923 -10% 684 816 928 1068
A98USMV090C20S
1 HP 11 x 11
50 - 80
Max.
Input
+15% 684 1136 1588
2nd
Stage
+10% 1335 1559 1719 1986
+7.5% 623 1059 1496 Default 1173 1433 1568 1811
Default 562 983 1403 -10% 1049 1283 1451 1603
35 - 65
Min.
Input
1st
Stage
+10% 911 1043 1227 1434
-7.5% 608 814 1020 Default 805 960 1087 1296
-15% 571 747 923 -10% 700 840 991 1115
A98USMV110C20S
1 HP 11 x 11
50 - 80
Max.
Input
+15% 733 1194 1747
2nd
Stage
+10% 1270 1519 1712 1899
+7.5% 708 1139 1657 Default 1170 1363 1555 1774
Default 683 1085 1566 -10% 1059 1218 1401 1581
35 - 65
Min.
Input
1st
Stage
+10% 918 1053 1198 1366
-7.5% 632 1007 1457 Default 820 964 1095 1231
-15% 580 929 1348 -10% 722 852 987 1116
A98USMV135D20S
1 HP 11 x 11
55 - 85
Max.
Input
+15% 1010 1505 2001
2nd
Stage
+10% 1337 1550 1720 1974
+7.5% 923 1398 1873 Default 1194 1416 1608 1781
Default 836 1290 1744 -10% 1076 1282 1437 1628
35 - 65
Min.
Input
1st
Stage
+10% 938 1070 1236 1418
-7.5% 775 1208 1641 Default 837 985 1114 1296
-15% 715 1126 1537 -10% 736 870 1010 1139
** See installation instructions for proper blower setup

508420-01 Issue 2345 Page 5 of 75
BLOWER PERFORMANCE: SIDE INLET WITH RETURN AIR BASE
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
UPFLOW / HORIZONTAL
A98USMV070B12S
1/2 HP 10 x 9
50 - 80
Max.
Input
+15% 519 805 1091
2nd
Stage
+10% 857 1049 1206 1354
+7.5% 480 751 1021 Default 791 946 1093 1255
Default 441 696 951 -10% 722 845 987 1131
35 - 65
Min.
Input
1st
Stage
+10% 596 717 816 950
-7.5% 408 643 877 Default 521 657 755 840
-15% 375 589 803 -10% 494 597 672 747
A98USMV090C12S
1/2 HP 10 x 9
60 - 90
Max.
Input
+15% 721 988 1254
2nd
Stage
+10% 852 999 1166 1305
+7.5% 679 923 1167 Default 776 907 1050 1206
Default 637 858 1079 -10% 712 802 947 1074
35 - 65
Min.
Input
1st
Stage
+10% 605 715 812 934
-7.5% 606 806 1006 Default 571 662 735 820
-15% 576 754 933 -10% 530 602 673 725
A98USMV090C16S
3/4 HP 11 x 11
50 - 80
Max.
Input
+15% 828 1213 1597
2nd Stage
+10% 1162 1360 1533 1742
+7.5% 766 1132 1499 Default 1064 1240 1400 1594
Default 703 1052 1401 -10% 928 1133 1298 1441
35 - 65
Min.
Input
1st
Stage
+10% 844 955 1124 1280
-7.5% 650 986 1323 Default 775 910 1011 1173
-15% 596 921 1245 -10% 695 816 932 1045
A98USMV090C20S
1 HP 11 x 11
60 - 90
Max.
Input
+15% 686 1138 1589
2nd Stage
+10% 1329 1560 1740 1982
+7.5% 626 1060 1494 Default 1177 1414 1586 1807
Default 566 983 1399 -10% 1044 1261 1432 1619
35 - 65
Min.
Input
1st
Stage
+10% 913 1037 1230 1415
-7.5% 502 895 1288 Default 827 953 1088 1278
-15% 437 806 1176 -10% 741 855 995 1117
A98USMV110C20S
1 HP 11 x 11
50 - 80
Max.
Input
+15% 893 1419 1945
2nd Stage
+10% 1268 1487 1726 1913
+7.5% 814 1329 1843 Default 1158 1369 1568 1764
Default 736 1238 1741 -10% 1030 1224 1393 1575
35 - 65
Min.
Input
1st
Stage
+10% 918 1022 1205 1371
-7.5% 680 1139 1599 Default 839 955 1084 1235
-15% 623 1040 1457 -10% 760 865 984 1109
A98USMV135D20S
1 HP 11 x 11
50 - 80
Max.
Input
+15% 992 1487 1983
2nd Stage
+10% 1303 1536 1687 1975
+7.5% 907 1382 1858 Default 1164 1380 1584 1762
Default 822 1277 1732 -10% 1065 1252 1404 1604
35 - 65
Min.
Input
1st
Stage
+10% 918 1061 1214 1382
-7.5% 761 1188 1615 Default 829 960 1091 1265
-15% 700 1099 1497 -10% 739 858 991 1116
** See installation instructions for proper blower setup

508420-01Issue 2345Page 6 of 75
ACCESSORY LIST
Catalog Number Description
External Filter Rack Kits
1.841018 1 pack (16 x 25)
1.841039 10 pack (16 x 25)
Natural to LP Kits
68W77 Modulating 97/98% (including gas valve)
68W77 High Altitude > 7500 ft.
Return Air Base
68W62 17.5" B Width
68W63 21.0" C Width
68W64 24.5” D Width
Downow Combustible Flooring Base
11M60 17.5" B Width
11M61 21.0" C Width
Night Service Kits
89W52 Modulating
Horizontal Suspension Kit
51W10 80% & 90% Kit
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)
For vent length and clearances to combustibles, please reference installation instructions.

508420-01 Issue 2345 Page 7 of 75
Figure 1.
BURNER BOX ASSEMBLY
VARIABLE
CAPACITY
GAS VALVE
HEAT EXCHANGER
ACCESS PANEL
CONTROL BOX
(includes variable capacity integrated control
transformer, circuit breaker and door switch)
VARIABLE SPEED BLOWER MOTOR
BAG ASSEMBLIES
(shipping location)
COLD END HEADER
BOX
PRESSURE SWITCHES
VARIABLE SPEED
COMBUSTION AIR
INDUCER
PRIMARY LIMIT
SHIPPING BLOCK
(-135 UNITS ONLY)
Parts Arrangement

508420-01Issue 2345Page 8 of 75
Unit Components
A98USMV 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. A98USMV units are factory-
equipped with a bottom return air panel in place. The panel
is designed to be eld removed as required for bottom air
return. Markings are provided for side return air and may
be cut out in the eld.
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.
Transformer
Integrated Control
Interlock Switch
Circuit Breaker
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. This control is used with the Comfort Sync®
thermostat as part of a communicating comfort system.
The control can also operate with a non-communicating
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 Table 13 under CODE, an “E” followed by
“2” followed by “5” followed by “0”, the limit switch circuit
is open. The control has a 120V humidier and a 120V
accessory terminal, both rated at (1) one amp each.

508420-01 Issue 2345 Page 9 of 75
Pin # Function
1Not Used
2High Fire Pressure Switch
3Rollout Switch In
4Ground
524V Hot
6Primary Limit In
7Gas Valve
8Gas Valve Common
9 24V 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.

508420-01Issue 2345Page 10 of 75
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
E44 INDOOR
L - use only with
communicating T'stat and
non-communicating outdoor
unit.
W915 Y1 TO Y2
W951 R TO O
W914 R TO DS
E43 E44
E3
RS-BUS LINK (E3, future use)
I+ = DATA HIGH CONNECTION
I - = DATA LOW CONNECTION
RS-BUS OUTDOOR (E43)
R = 24VAC
I + = DATA HIGH CONNECTION
I - = DATA LOW CONNECTION
C = 24VAXC COMMON
RS-BUS INDOOR (E44)
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. DO NOT CONNECT TO
COMFORT SYNC® THERMOSTAT
L=USE ONLY WITH A COMMUNICATING THERMOSTAT
AND A NON-COMMUNICATING OUTDOOR UNIT
DH =DEHUMIDIFICATION OUTPUT COMMUNICATING
THERMOSTAT ONLY
Figure 4. Integrated Control

508420-01 Issue 2345 Page 11 of 75
Figure 5. Integrated Control Conguration Guide

508420-01Issue 2345Page 12 of 75
Operation Thermostat Switch 1 Switch 2 Switch 3
Variable Capacity Heat
(40% to 100%) Two-Stage O󰀨 On O󰀨
Three-Stage Heat
(40%, 70%, 100%) Single-Stage On O󰀨
2nd Stage Delay
OF = 7 minutes
ON = 12 minutes
3rd Stage Delay
10 minutes xed
Two-Stage Heat
(W1 70%, W2 100%) Two-Stage O󰀨 O󰀨 O󰀨
Table 3. Thermostat Selection Switch Settings
NOTE: When the A98USMV is used with an Comfort
Sync Wi-Fi®communicating thermostat, all indoor blower
speed selections and DIP switch settings are made by the
communicating thermostat.
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

508420-01 Issue 2345 Page 13 of 75
will continue 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󰀨
CO󰀨 On
D On 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 through 19 -- 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

508420-01Issue 2345Page 14 of 75
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 14
for operation sequence in applications including A98USMV,
a thermostat which features humidity control and a single-
speed outdoor unit. Table 15 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.
Table 13 lists diagnostic LED codes.
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.

508420-01 Issue 2345 Page 15 of 75
• 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.
Soft Disable
Soft disabling is when thermostat nds a device on the
BUS that it does not recognize and the thermostat sends
a the device a message to be in soft disabling mode until
properly congured. Two horizontal bars will display.
Steps to follow if the damper control module is displaying
the soft disable code.
1. Conrm proper wiring between all devices (thermostat,
damper control module, indoor and outdoor).
2. Cycle power to the control that is displaying the soft
disable code.
3. Put the room thermostat through set up.
4. Go to setup / system devices / thermostat / edit / then
push reset.
5. Go to setup / system devices / thermostat / edit / then
push resetAll.
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

508420-01Issue 2345Page 16 of 75
Conguring Unit Size Codes
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.
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
UNIT SIZE
CODE FURNACE MODEL
1A98USMV070B12S
2A98USMV090C12S
3A98USMV090C16S
4A98USMV090C20S
5A98USMV110C20S
6A98USMV135D20S

508420-01 Issue 2345 Page 17 of 75
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.
UDischarge Air Temperature
E105 Device communication problem - No other
devices on RS BUS (Communication system).
Equipment is unable to communicate. Indicates numerous message
errors. In most cases, errors are related to electrical noise. Make sure
high voltage power is separated from RSBus. Check for mis-wired and/or
loose connections between the stat, indoor unit, and outdoor unit. Check
for a high voltage source of noise close to the system. Fault clears after
communication is restored.
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.
E120 Unresponsive device (Communicating systems
only).
Usually caused by delay in outdoor unit responding to indoor unit poling.
Recycle power. Check all wiring connections. Cleared after unresponsive
device responds to any inquiry.
E124 Active communicating thermostat signal missing
for more than 3 minutes (Communicating systems
only).
Equipment lost communication with the thermostat. Check four wiring
connections, ohm wires, and cycle power at the thermostat. Alert stops
all services and waits for heartbeat message from thermostat (subnet
controller). Cleared after valid thermostat (subnet) message is received.
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.
E131 Corrupted control parameters (Verify
conguration of system) (Communicating systems
only).
Recongure the system. Replace control if heating or cooling is not
available. Only applicable in the communicating mode not in startup. Exit
from Commissioning and Execute Se+ factory Default mode. Control will
still operate on default parameter settings.
Table 13. Integrated Diagnostic Codes/Status of Equipment

508420-01Issue 2345Page 18 of 75
Code Diagnostic Codes / Status of Equipment Action Required to Clear and Recover
E180 Outdoor air temperature sensor failure. Only
shown if shorted or out of range (Communicating
systems only)
Compare outdoor sensor resistance to temperature resistance charts
in unit installation instructions. Replace sensor pack if necessary. At
beginning of (any) conguration, furnace or air handler control will sense
outdoor air and discharge air temperature sensor(s) If detected (reading
in range), appropriate feature will be set as installed and that could be
seen in 'About ' screen. In normal operation after control recognizes
sensors, alarm will be sent if valid temperature reading is lost. To get rid
of setting and alarm, redo conguration and make sure that temperature
sensor is marked as not installed in indoor Unit ‘About’ screen. When
indoor unit control is replaced thermostat will ‘tell’ new control if
temperature sensor is in system or not. Clears 30 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.
E202 Indoor blower motor mis-match - 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 10M. 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.
Table 13. Integrated Diagnostic Codes/Status of Equipment

508420-01 Issue 2345 Page 19 of 75
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 Watchguard 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.
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
in Communicating mode 30 seconds after fault recovered. In Non-
Communicating mode cleared after the current heat call is completed.
Table 13. Integrated Diagnostic Codes/Status of Equipment

508420-01Issue 2345Page 20 of 75
Code Diagnostic Codes / Status of Equipment Action Required to Clear and Recover
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 preset 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.
E313 Indoor or outdoor unit capacity mismatch.
Communication only.
Incorrect indoor/outdoor capacity code selected. Check for proper
conguring in installation instructions. Alarm is just a warning. The system
will operate, but might not meet e󰀩ciency and capacity parameters.
Alarm will clear when commissioning is complete.
E331 Global network connection - Communications link
problem.
For Future Use.
E347 No 24 Volt output on Y1 of "integrated control"
with non-communicating 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 non-communicating 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 non-communicating outdoor
unit (dual fuel model required for heat pump
application).
Conguration link R to O needs to be restored. Replace link or hardware.
Applicable in non-communicating mode. Critical Alert.
E401 LSOM - Compressor long run cycle or low system
pressure.
Compressor ran more that 18 hours to satisfy a single thermostat
demand. Critical Alert. Clears the error after 30 consecutive normal run
cycles or power reset. Also monitors low pressure switch trips.
E402 LSOM - Outdoor unit system pressure trip. Discharge or suction pressure out-of-limits, or compressor overloaded.
Clears the error after 4 consecutive normal compressor run cycles.
E403 LSOM - Compressor short-cycling (Running less
than 4 minutes). Outdoor unit pressure trip.
Compressor runs less than 3 minutes to satisfy a thermostat demand.
Clears the error after 4 consecutive normal run cycles or power reset.
E404 LSOM - Compressor rotor locked. Compressor
short-cycling. (Running less than 4 minutes.)
Compressor rotor locked up due to run capacitor shore, bearings
are seized, excessive liquid refrigeration, etc. Clears the error after 4
consecutive normal run cycles or power reset.
E405 LSOM - Compressor open circuit. Compressor circuit open (due to power disconnection, open fuse, etc.)
Clears the error after 1 normal compressor run cycle.
E406 LSOM - Compressor open start circuit. Required amount of current is not passing through Start current
transformer. Clears the error after current is sensed in START sensor, or
after power reset.
E407 LSOM - Compressor open run circuit. Required amount of current is not passing through Run current
transformer. Clears the error after current is sensed in RUN sensor, or 1
normal compressor run cycle, or after power reset.
E408 LSOM - Compressor contactor is welded. Compressor runs continuously. Clears the error after 1 normal
compressor run cycle or after power reset.
E409 LSOM - Compressor low voltage. Secondary voltage s below 18VAC. After 10 minutes, operation is
discontinued. Clears the code after voltage is higher than 20VAC for 2
seconds or after power reset.
Table 13. Integrated Diagnostic Codes/Status of Equipment