Lennox SL280DF110V60C Installation and operation manual

Page 1 ©2016 Lennox Industries Inc.
Corp. 1117-L4 SL280DFV
Service Literature Revised 06-2016
icomfort®ENABLED SL280DFV SERIES UNITS
SL280DFV series units are 80% efficiency gas furnaces
used for downflow applications only, manufactured with
Lennox Duralokheat exchangers formed of aluminized
steel. Units are available in heating capacities of 66,000 to
110,000 Btuh and cooling applications up to 5 tons. Refer to
Engineering Handbook for proper sizing.
Units are factory equipped for use with natural gas. Kits are
available for conversion to LPG operation. SL280DFV mod
el units are equipped with the icomfort®enabled SureLight®
two-stage variable speed integrated control. All units use a
redundant gas valve to assure safety shut-off as required by
CSA.
All specifications in this manual are subject to change. Pro
cedures outlined in this manual are presented as a recom
mendation 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 consti
tute code.
TABLE OF CONTENTS
Specifications Page 2.............................
Parts Identification Page 3.........................
I Unit Components Page 4........................
II Installation Page 29............................
III Start Up Page 29..............................
IV Heating System Service Checks Page 31.........
V Typical Operating Characteristics Page 34.........
VI Maintenance Page 34..........................
VII Wiring and Sequence of Operation Page 38......
VIII Program Unit Capacity Size Mode Page 42......
IX Field Wiring and Jumper Settings Page 43........
X Troubleshooting Flow Chart Page 47..............
WARNING
Improper installation, adjustment, alteration, service
or maintenance can cause property damage, person
al injury or loss of life. Installation and service must
be performed by a licensed professional HVAC in
staller (or equivalent), service agency or the gas sup
plier.
WARNING
Electric shock hazard. Can cause injury
or death. Before attempting to perform
any service or maintenance, turn the
electrical power to unit OFF at discon
nect switch(es). Unit may have multiple
power supplies.
CAUTION
As with any mechanical equipment, contact with
sharp sheet metal edges can result in personal in
jury. Take care while handling this equipment and
wear gloves and protective clothing.

Page 2
SPECIFICATIONS
Gas
Heating
Performance
Model No. SL280DF070V36A SL280DF090V48B SL280DF090V60C SL280DF110V60C
1AFUE 80% 80% 80% 80%
High
Fire
Input - Btuh 66,000 88,000 88,000 110,000
Output - Btuh 52,000 69,000 70,000 87,000
Temperature rise range - °F 35-65 35-65 35-65 35-65
Gas Manifold Pressure (in. w.g.)
Nat. Gas / LPG/Propane
3.5 / 10.0 3.5 / 10.0 3.5 / 10.0 3.5 / 10.0
Low
Fire
Input - Btuh 43,000 57,000 57,000 72,000
Output - Btuh 35,000 46,000 46,000 59,000
Temperature rise range - °F 25-55 25-55 25-55 25-55
Gas Manifold Pressure (in. w.g.)
Nat. Gas / LPG/Propane
1.7 / 4.9 1.7 / 4.9 1.7 / 4.9 1.7 / 4.9
High static - in. w.g. Heating 0.8 0.8 0.8 0.8
Cooling 1.0 1.0 1.0 1.0
Connections
in.
Flue connection - in. round 4 4 4 4
Gas pipe size IPS 1/2 1/2 1/2 1/2
Indoor
Blower
Wheel nominal diameter x width - in. 10 x 8 11 x 9 11 x 10 11 x 10
Motor output - hp 1/2 1 1 1
Tons of add-on cooling 2 - 3 3 - 4 3.5 - 5 3.5 - 5
Air Volume Range - cfm 589 - 1514 830 - 1996 899 - 2273 882 - 2120
Electrical
Data
Voltage 120 volts - 60 hertz - 1 phase
Blower motor full load amps 7.7 12.8 12.8 12.8
Maximum overcurrent protection 15 20 20 20
Shipping Data lbs. - 1 package 130 153 164 173
NOTE - Filters and provisions for mounting are not furnished and must be eld provided.
1 Annual Fuel Utilization Efciency based on DOE test procedures and according to FTC labeling regulations. Isolated combustion system rating for non-weatherized
furnaces.
OPTIONAL ACCESSORIES - MUST BE ORDERED EXTRA
“A” Width
Models
“B” Width
Models
“C” Width
Models
CABINET ACCESSORIES
Downow Combustible Flooring Base 11M59 11M60 11M61
CONTROLS
ComfortSense®7000 Thermostat Y0349 Y0349 Y0349
Remote Outdoor Sensor (for dual fuel and Humiidtrol®) X2658 X2658 X2658
DOWNFLOW FILTER KITS
Downow Filter Kit 51W06 51W07 51W08
No. and Size of lter - in. (1) 20 x 16 x 1 (2) 20 x 20 x 1 (2) 20 x 20 x 1
NIGHT SERVICE KITS
Night Service Kit 16S36 16S36 16S36
Safety Service Kit 89W19 89W19 89W19
GAS HEAT ACCESSORIES
Models Natural Gas to
LPG/Propane Kit
LPG/Propane to
Natural Gas Kit
all 11K51 11K46

Page 3
FIGURE 1
PARTS IDENTIFICATION
BLOWER ASSEMBLY
INTERNAL FLUE
PIPE ASSEMBLY
FLUE CHASE
GASKET
DOOR INTERLOCK SWITCH
HEAT EXCHANGER
COMBUSTION AIR INDUCER
COMBUSTION AIR INDUCER
PRESSURE SWITCHES
GAS VALVE
BURNER BOX ASSEMBLY
INNER BLOWER ACCESS PANEL
ACCESS PANEL
CONTROL BOX
(Includes two-stage integrated control,
transformer and circuit breaker)
ROLLOUT SWITCH
PRIMARY LIMIT LOCATION
SECONDARY LIMIT

Page 4
I-UNIT COMPONENTS
Unit components are shown in figure 1. The gas valve,
combustion air inducer and burners can be accessed by re
moving the access panel. Electrical components are in the
control box (figure 2) found in the blower section.
CAUTION
Electrostatic discharge can affect elec
tronic components. Take precautions
to neutralize electrostatic charge by
touching your hand and tools to metal
prior to handling the control.
A- Control Box
1. 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 sec
ondary.
2. Door Interlock Switch (S51)
An interlock switch rated 14A at 125VAC is wired in series
with line voltage. When the indoor blower access panel is
removed the unit will shut down.
FIGURE 2
CONTROL BOX SL280DFV
SureLight®Integrated Control
Interlock Switch
Transformer
Circuit Breaker
3. Circuit Breaker (CB8)
A 24V circuit breaker is also located in the control box.
The switch provides overcurrent protection to the trans
former (T1). The breaker is rated 3A at 32V. If the current
exceeds this limit the breaker will trip and all unit opera
tion will shutdown. The breaker can be manually reset
by pressing the button on the face. See figure 3.
FIGURE 3
CIRCUIT BREAKER CB8
PRESS TO RESET
WARNING
Shock hazard.
Disconnect power before servicing. Integrated
control is not field repairable.
If control is inoperable, simply replace entire con
trol.
Can cause injury or death. Unsafe operation will
result if repair is attempted.
4. SureLight Integrated Control (A92)
Units are equipped with the icomfortenabled Sur
eLight®two-stage, variable speed integrated control. This
control is used with the icomfort Wi-Fi®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 a ignition /
blower control (figures 4 and 5) with control pin designa
tions in tables 1, 2 and 3 and ignitor (figure 13). 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 flame signal. The control features a seven-seg
ment LED display, indicating furnace status (including in
door blower) and error codes. The LED flashes in single
digits. For example using table 5 under LIMIT CODE, an
“E” followed by “2” followed by “5” followed by “0”, the limit
switch circuit is open. The control also has two unpowered
(dry) 1/4” contacts for a humidifier and a 120 volt accessory
terminal. Both rated at (1) one amp each.
Electronic Ignition
At the beginning of the heat cycle the integrated control
monitors the first stage and second stage combustion air
inducer prove switch. The control will not begin the heating
cycle if the first stage prove switch is closed (by-passed).
Likewise the integrated control will not begin the second
stage heating cycle if the second stage prove switch is
closed, and will remain in first stage heat. However, if the
second stage prove switch closes during the first stage
heat pre-purge, the control will allow second stage heat.
Once the first stage prove switch is determined to be open,

Page 5
the combustion air inducer is energized on low (first stage)
heat speed. When the differential in the prove switch is
great enough, the prove switch closes and a 15-second
pre-purge begins.
NOTE - During abnormal conditions such as low supply
voltage or low outdoor temperatures and the low fire pres
sure switch does not close, the combustion air inducer will
switch to high fire. After a 15 second pre-purge the high fire
pressure switch will close and the unit will begin operation
on high fire. After 10 to 20 seconds of high fire operation the
unit will switch to low fire
After the 15-second pre-purge period, the SureLight ignitor
warms up for 20 seconds after which the gas valve opens
for a 4-second trial for ignition. The ignitor energizes during
the trial until flame is sensed. If ignition is not proved during
the 4-second period, the control will try four more times with
an inter purge and warm-up time between trials of 35 sec
onds. After a total of five trials for ignition (including the ini
tial trial), the control goes into Watchguard-Flame Failure
mode. After a 60-minute reset period, the control will begin
the ignition sequence again.
Two Stage Operation / Thermostat Selection DIP
Switch
The control can be utilized in two modes: SINGLE-STAGE
thermostat or TWO-STAGE thermostat. The thermostat
selection is made using a DIP switch and must be posi
tioned for the particular application. DIP switch 1, labeled
T”STAT HEAT STAGE is factory-set in the OFF position for
use with a two-stage thermostat. Move the DIP switch to
ON for use with a single stage thermostat.
While in the single-stage thermostat mode (single DIP
switch setting), the burners will always fire on first-stage
heat. The combustion air inducer will operate on low speed
and indoor blower will operate on low heat speed. After a
factory default 10 minute recognition period, the unit will
switch to second stage heat. While in the two-stage ther
mostat mode (two DIP switch setting) the burners will fire
on first-stage heat. The combustion air inducer will operate
on low speed and indoor blower will operate on low heat
speed. The unit will switch to second-stage heat on call
from the indoor thermostat. If there is a simultaneous call
for first and second stage heat, the unit will fire an first stage
heat and switch to second stage heat after 30 seconds of
operation. See Sequence of Operation flow charts in the
back of this manual for more detail.
TABLE 1
SureLight®Control 5 Pin Terminal Designation
PIN # Function
1 Ignitor
2Combustion Air Inducer High Speed
3Combustion Air Inducer Low Speed
4Combustion Air Inducer Neutral
5Ignitor Neutral
TABLE 2
SureLight®Control 12 Pin Terminal Designation
PIN # Function
1Gas Valve High Fire
2Second Stage Prove Switch
3Rollout In
4 Ground
524V Hot
6Primary Limit In
7Gas Valve Low Stage
8Gas Valve Common
924V Neutral
10 Ground
11 Rollout Switch Out
12 1st Stage Prove Switch
TABLE 3
SureLight®Control 6 Pin Terminal Designation
PIN # Function
1Data Input From Motor
2 Common
3Not Used
4Data Output To Motor
55 Volt Bias Supply
6Not Used

Page 6
FIGURE 4
THERMOSTAT CONNECTIONS (TB1)
1/4” QUICK CONNECT TERMINALS
RS-BUS LINK (TB82, future use)
I+ = DATA HIGH CONNECTION
I - = DATA LOW CONNECTION
RS-BUS OUTDOOR (TB83)
R = 24VAC
I + = DATA HIGH CONNECTION
I - = DATA LOW CONNECTION
C = 24VAC COMMON
RS-BUS INDOOR (TB84)
R = 24VAC
I + = DATA HIGH CONNECTION
I - = DATA LOW CONNECTION
C = 24VAC COMMON
FLAME SENSE
DIP SWITCHES
OUTDOOR AIR
SENSOR
TERMINALS
DISCHARGE AIR
SENSOR
TERMINALS
INDOOR
BLOWER
CONNECTOR
NEUTRAL
DIAGNOSTIC
PUSH BUTTON
TB83
COMMUNICATING
OUTDOOR
EQUIPMENT
TB84
COMMUNICATING
INDOOR
THERMOSTAT
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 T'STAT
C = THERMOSTAT SIGNAL GROUND CONNECTED 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
L = USE ONLY WITH A COMMUNICATING THERMOSTAT
AND A NON-COMMUNICATING OUTDOOR UNIT
DH = DEHUMIDIFICATION OUTPUT COMMUNICATING
THERMOSTAT ONLY
HUM = UNPOWERED NORMALLY OPEN (DRY) CONTACTS
XMFR = 120 VAC OUTPUT TO TRANSFORMER
LI = 120 VAC INPUT TO CONTROL
ACC = 120 VAC OUTPUT TO OPTIONAL ACCESSORY
NEUTRALS = 120 VAC NEUTRAL
W915 Y1 TO Y2
2 STAGE COMPR
W951 R TO O
HEAT PUMP
W914 R TO DS
DEHUM OR
HARMONY
W1 W2 G Y2 Y1 CCRDHLODS
RI + I - CRI + I - C
7 SEGMENT LED
ACC
LINE 1
HUM
12 PIN LOW
VOLTAGE
CONNECTOR
NON-COMMUNICATINGNG
24V TERMINALS
HS/ CAI
INTEGRATED CONTROL

Page 7
FIGURE 5
HEATING BLOWER−OFF DELAY
60 SECOND
HTG BLOWER
OFF DELAY
120 SECOND
HTG BLOWER
OFF DELAY
180 SECOND
HTG BLOWER
OFF DELAY
FLAME
15
HSI/CAI
2ND STAGE HEAT ON DELAY
7 MIN
UPSTAGE
DELAY
12 MIN
UPSTAGE
DELAY
*CONTINUOUS FAN MODE BLOWER SPEED
COOLING MODE BLOWER RAMPING
CLG BLOWER SPEED ADJUSTMENT
COOLING MODE BLOWER SPEED
W915
2 STAGE
COMPR
1−STG COMPRESSOR
2−STAGE
COMPRESSOR LINK
(JUMPERS Y1 to Y2)
W915
DO NOT CUT
2−STG COMPRESSOR
HEAT PUMP LINK
(JUMPERS R to O)
W951
DEHUMIDIFICATION−
HARMONY LINK
(JUMPERS R to DS)
W914
W915
2 STAGE
COMPR
CUT LINK
A/C UNIT
DO NOT CUT
HEAT PUMP UNIT
CUT LINK
W951
HEAT
PUMP
W951
HEAT
PUMP
W914
DEHUM
or
NO HARMONY ZONING
OR
NO SIGNATURESTAT
W/ DS CONNECTION
DO NOT CUT
HARMONY ZONING
OR
SIGNATURESTAT W/
DS CONNECTION
CUT LINK
HARMONY
W914
DEHUM
or
HARMONY
1
1
1
ON−BOARD LINK
OPTION SELECTION
1234567
1234567
123567
4
123567
4
NEUTRALS
L1
ACC
HUM
14
36
P79
110
312
J2
4 7
W915
2 STAGE
COMPR
W951
HEAT
PUMP
W914
DEHUM
HARMONY
CUT FOR
OPTION
SELECTION
OUTDOOR SENSOR
DISCHARGE AIR SENSOR
123456
10 12
911
13
ON
ON
SureLight®
W1W2 GY2 Y1 C C DHL O DSR
W1 W2
G
Y2 Y1
C C
R
L
DH
HIGH
SPEED
(100%)
MEDIUM−HIGH
SPEED
(70%)
MEDIUM−LOW
SPEED
(38%)
LOW
SPEED
(28%)
*
OPTION A
OFF−50%−82%−
100%−50%−OFF
OPTION B
OFF−82%−100%−OFF
OPTION C
OFF−100%−100%−OFF
OPTION D
OFF−100%−OFF
*
DEFAULT
+ 10%
− 10%
*
HIGH
SPEED
MEDIUM−HIGH
SPEED
MEDIUM−LOW
SPEED
LOW
SPEED
*
7
−PROTECTIVE PLASTIC FILM ON DIP SWITCHES MAY BE
REMOVED FOR EASE IN SETTING OF DIP SW.
−CUT ON−BOARD LINK (SOLDER TRACE) COMPLETELY THROUGH
BOTH LAYERS ON THE CONTROL BOARD
−LINKS CUT IN ERROR −INSTALL A JUMPER ON THE APPROPRIATE
TERMINALS ON THE TERMINAL STRIP
1
910 11 12 13 14
ON
ON
ON
ON
ON
ON
ON
ON
90 SECOND
HTG BLOWER
OFF DELAY
*1234567
ON
1234567
ON
THERMOSTAT SELECTION
1−STAGE
THERMOSTAT
(TIMED STAGING)
−SEE SW #2
TWO STAGE
THERMOSTAT
*1234567
1234567
ON
ON
−BLOWER ON DELAY − 30 SEC. FIXED
15
910 11 12 14 15
910 11 12 14 15
910 11 12 14 15
8
8
8
8
8
8
8
81234567
1234567
ON
ON
1234567
ON
1234567
ON
8
8
8
8
910 11 12 13 14
ON
ON
ON
ON
15
910 11 12 14 15
910 11 12 14 15
910 11 12 14 15
910 11 12 13 14
ON
ON
ON
ON
15
910 11 12 14 15
910 11 12 14 15
910 11 12 14 15
HEATING MODE BLOWER SPEED
1234567
ON
1234567
ON
1234567
ON
8
8
8
910 11 12 13 14
ON
ON
ON
ON
15
910 11 12 14 15
910 11 12 14 15
910 11 12 14 15
FACTORY
DEFAULT
+ 24%
+ 18%
+ 12%
+ 6%
− 6%
− 12%
− 18%
8
14 15
INCREASE AIR HTG CFM
DECREASE AIR HTG CFM
SENSE
RI+ I− CRI+ I− C
OUTDOOR EQUIPMENT
I+ I−
INDOOR EQUIPMENT
IGN
CAI2
CAI1
N N
J3
S1
S4S3
13
13
13
13
13
13
13
* FACTORY DEFAULT
13
13
*
DIAGNOSTIC
LED
DIAGNOSTIC
PUSH BUTTON
INTEGRATED CONTROL CONFIGURATION GUIDE

Page 8
TABLE 4
Integrated Control Diagnostic Modes
Display Action (when button released)
No change (idle)* Remain in idle mode
Solid “E” Enter diagnostic recall mode
Solid “D” Discharge Air Installed
Solid “F” Enter flame signal mode
Solid “P” (variable speed only) Program unit capacity/size (Unit Code)
* No change implies the display will continue to show whatever is currently being displayed for normal operation (blinking
decimal, active error code, heat state, etc..)
Diagnostic LED (Figure 4)
The seven-segment diagnostic LED displays operating
status, target airflow, error codes and other information.
The table beginning on Page 9 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 en
able the Error Code Recall “E” mode and the Flame Signal
“F” mode. Press the button and hold it to cycle through a
menu of options. Every five 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 flashing to confirm command to delete codes.
Press the button until a solid “≡” is displayed to exit the Error
Code Recall mode.
Flame Signal Mode
Select ”F” from the menu to access the flame signal mode.
The integrated control will display the flame current on 7
segment LED in in micro amps (uA).
Flame signal mode is exited after any of the following:
Power is reset
Pressing and holding push button until 3 horizontal
lines “≡” are displayed
10 minutes after entering the flame sense mode.
Program Unit Capacity/Size Mode
After the “P” is selected (by releasing the push button) the
integrated control will start flashing the “P” on display for 90
seconds. If push button is pressed again and held during
that time, the control will start to display characters corre
sponding to different variable speed furnace models for 3
seconds each. While the wanted character-model is dis
played push button has to be released. Selected option will
flash display for 10 seconds and during that time push but
ton has to be pressed and held for 5 seconds. Once control
accepts new setting it will store data in non-volatile memory
and reset itself. If 10 seconds expires or push button is held
less than 5 seconds, control will exit field test mode and go
into idle without changing programming the unit size.

Page 9
TABLE 5
Integrated Diagnostic Codes/Status of Equipment I.
Code Diagnostic Codes/Status of Equipment Action Required to Clear and Recover
.Idle mode (Decimal blinks at 1 Hertz -- 0.5 second ON, 0.5 second OFF).
ACubic feet per minute (cfm) setting for indoor blower (1 second ON, 0.5
second OFF) / cfm setting for current mode displayed.
CCooling stage (1 second ON, 0.5 second OFF) / 1 or 2 displayed / Pause
/ cfm setting displayed / Pause / Repeat codes).
dDehumidification mode (1 second ON) / 1 second OFF) / cfm setting dis
played / Pause / Repeat Codes).
hHeat pump stage (1 second ON, 0.5 second OFF) / % of input rate dis
played / Pause / cfm setting / Pause / Repeat codes.
HGas Heat Stage (1 second ON, 0.5 second OFF) / 1 or 2 displayed /
Pause / cfm
setting displayed / Pause / Repeat codes. Blinking during ignition.
dF Defrost mode.
UDischarge Air Temperature
E 105 Device communication problem - No other devices on RS BUS (Commu
nication
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 volt
age source of noise close to the system. Fault
clears after communication is restored.
E 110 Low line voltage. Line Voltage Low (Voltage lower than nameplate
rating). Check power line voltage and correct. Alarm
clears 5 seconds after fault recovered.
E 111 Line voltage polarity reversed. Reverse line power voltage wiring. System resumes
normal operation 5 seconds after fault recovered.
E 112 Ground not detected System shuts down. Provide proper earth ground.
System resumes normal operation 5 seconds after
fault recovered.
E 113 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.
E 114 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.
E 115 Low 24V - Control will restart if the error recovers. 24-Volt Power Low (Range is 18 to 30 volts). Check
and correct voltage. Check for additional power-rob
bing equipment connected to system. May require
installation of larger VA transformer to be installed
in furnace / air handler. Clears after fault recovered.
E 116 High 24V. 24 Volt Power High (Range is 18 to 30 volts). Check
and correct voltage. Check for proper line voltage
(120V, 240V, etc.) to equipment. Clears when con
trol senses proper voltage.
E 117 Poor ground detected (Warning only) Provide proper grounding for unit. Check for proper
earth ground to the system. Warning only will clear
30 seconds after fault recovered.
E 120 Unresponsive device. Communication only. Usually caused by delay in outdoor unit responding
to indoor unit poling. Recycle power. Check all wir
ing connections. Cleared after unresponsive device
responds to any inquiry.

Page 10
TABLE 5 Continued
Code Diagnostic Codes/Status of Equipment Action Required to Clear and Recover
E 124 Active communicating thermostat signal missing for more than 3 min
utes.
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 (sub
net controller). Cleared after valid thermostat (sub
net controller) message is received.
E 125 Control failed self-check, internal error, failed hardware. Will restart if
error
recovers. Integrated control not communicating. Covers hardware errors
(flame sense circuit faults, pin shorts, etc.).
Hardware problem on the control. Cycle power on
control. Replace if problem prevents service and is
persistent. Critical alert. Cleared 300 seconds after
fault recovered.
E 126 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 recov
ered.
E 131 Corrupted control parameters (Verify configuration of system). Communi
cating only.
Reconfigure the system. Replace control if heating
or cooling is not available. Only applicable in the
communicating mode, not in startup. Exit from Com
missioning and Execute 'Set Factory Default mode'.
Control will still operate on default parameter set
tings.
E 180 Outdoor air temperature sensor failure. Only shown if shorted or out-of-
range.
Compare outdoor sensor resistance to temperature/
resistance charts in unit installation instructions.
Replace sensor pack if necessary. At beginning of
(any) configuration, furnace or air handler control
will sense outdoor air and discharge air temperature
sensor(s). If detected (reading in range), appropri
ate 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 set
ting and alarm, redo configuration and make sure
that temperature sensor is marked as 'not installed'
in Indoor Unit 'About' screen. When Indoor unit con
trol is replaced, thermostat will 'tell' new control if
temperature sensor is in system or not. Clears 30
seconds after fault recovered.
E 200 Hard lockout - Rollout circuit open or previously open. Correct cause of rollout trip, or replace flame rollout
switch. Test furnace operation. Cleared after fault
recovered.
E 201 Indoor blower communication failure - Unable to communicate with blow
er motor.
Indoor blower communication failure (including pow
er 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.
E 202 Indoor blower motor mis-match - Indoor motor horsepower does not
match unit capacity. See Page 41.
Incorrect appliance capacity code selected. Check
for proper configuring under: Unit Size Codes for
Furnace/Air Handler on configuration guide or in
installation instructions. Cleared after the correct
match is detected following a reset. (Remove ther
mostat from system while applying power and re
programming.)
E 203 Appliance capacity / size is NOT programmed. Invalid unit codes refer to
configuration flow chart. See Page 41.
No appliance capacity code selected. Check for
proper configuring under: Unit Size Codes for Fur
nace on configuration guide or in installation instruc
tions. Critical Alert. Cleared after valid unit code is
read following a reset. (Remove thermostat from
system while applying power and reprogramming.)
E 204 Gas valve mis-wired. Check gas valve operation and wiring. Clears when
repaired.
E 205 Gas valve control relay contact shorted. Check wiring on control and gas valve. If wiring is
correct, replace control.

Page 11
TABLE 5 Continued
Code Diagnostic Codes/Status of Equipment Action Required to Clear and Recover
E 206 Gas valve second-stage relay failure Furnace will operate on 1st stage for remainder of
the heating demand. Will clear after fault recovered.
If unable to operate 2nd stage, replace control.
E 207 Hot surface ignitor sensed open - Refer to troubleshooting. SeePage 46. Measure resistance of hot surface ignitor. Replace if
open or not within specified range found in IOM.
Resumes normal operation after fault is cleared.
E 223 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 in
ducer for correct operation and restriction. Re
sumes normal operation after fault is cleared
E 224 Low pressure switch failed closed - Refer to troubleshooting. See
Page 46.
Check operation of low pressure switch to see if it is
stuck closed on heat call longer than 150 seconds.
Measure operating pressure (inches w.c.). Inspect
vent and combustion air inducer for correct opera
tion and restriction. Resumes normal operation after
fault is cleared.
E 225 High pressure switch failed open - Refer to troubleshooting. See
Page 46.
Check pressure (inches w.c.) of high pressure
switch closing on heat call. Measure operating pres
sure (inches w.c.). Inspect vent and combustion air
inducer for correct operation and restriction. Re
sumes normal operation after fault is cleared.
E 226 High pressure switch failed closed - Refer to troubleshooting. See
Page 46.
Check operation 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 opera
tion after fault is cleared.
E 227 Low pressure switch open during trial for ignition or run mode. Refer to
troubleshooting. See Page 46.
Check pressure (inches w.c.) of low pressure switch
closing on heat call. Measure operating pressure
(inches w.c.). Inspect vent and combustion air in
ducer for correct operation and restriction. Re
sumes normal operation after fault is cleared.
E 228 Combustion air inducer calibration failure Unable to perform pressure switch calibration.
Check vent system and pressure switch wiring con
nections. Resumes normal operation after fault is
cleared.
E 229 Ignition on High Fire - Information Only Code is displayed if 1) low pressure switch fails to
close, then furnace will switch to high speed inducer
to close both low and high pressure switches, then
furnace lights on high fire, or 2) if continuous fan is
active, furnace lights on high fire for 60 seconds to
improve heat exchanger warm up time.
E 240 Low flame current - Run mode - Refer to troubleshooting. See Page 46. Check micro-amperes of flame sensor using control
diagnostics or field-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.
E 241 Flame sensed out of sequence - Flame still present. Shut off gas. Check for gas valve leak. Replace, if
necessary. Alert clears when fault is recovered.
E 250 Limit switch circuit open - Refer to troubleshooting. See Page 46 Check for proper firing rate on furnace. Ensure
there is no blockage in heater. Check for proper air
flow. If limit not closed within 3 minutes, unit will go
into 1-hour soft lockout. Resumes normal operation
after fault is cleared.
E 252 Discharge air temperature too high (gas heat only). Check temperature rise, air flow and input rate.
Cleared when heat call is finished.
E 270 Soft lockout - Exceeded maximum number of retries. No flame current
sensed.
Check for proper gas flow. Ensure that ignitor is
lighting burner. Check flame sensor current. Clears
when heat call finishes successfully.

Page 12
TABLE 5 Continued
Code Diagnostic Codes/Status of Equipment Action Required to Clear and Recover
E 271 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 in
ducer for correct operation and restriction. Clears
when heat call finishes successfully.
E 272 Soft lockout - Exceeded maximum number of recycles. Last recycle due
to the pressure switch opening.
Check operation of low pressure switch 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 (inches w.c.). Inspect
vent and combustion air inducer for correct opera
tion and restriction. Clears when heat call finishes
successfully.
E 273 Soft lockout - Exceeded maximum number of recycles. Last recycle due
to flame failure.
Check micro-amperes of flame sensor using control
diagnostics or field-installed mode. Clean or replace
sensor. Measure voltage of neutral to ground to
ensure good unit ground. Clears when heat call
finishes successfully.
E 274 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 firing
rate and air flow. Check for blockage. Clears when
heat call finishes successfully.
E 275 Soft lockout - Flame sensed out of sequence. Flame signal is gone. Shut off gas. Check for gas valve leak. 1-hour soft
lockout. Clears when flame has been proven stable.
E 276 Watchguard calibration failure. Unable to perform pressure switch calibration.
Check vent system and pressure switch wiring con
nections. 1-hour soft lockout. Clears when calibra
tion has finished successfully.
E 290 Ignitor circuit fault - Failed ignitor or triggering circuitry. Measure resistance of hot surface ignitor. Replace if
open or not within specifications. 1-hour soft lock
out. Clears when flame has been proven stable.
E 291 Heat air flow restricted below the minimum. Check for dirty filter and air flow restriction. Check
blower performance. 1-hour soft lockout. Cleared
when heat call finishes successfully.
E 292 Indoor blower motor unable to start due to obstructed wheel, seized
bearings.
Indoor blower motor unable to start (seized bear
ing, stuck wheel, etc.). Replace motor or wheel if
assembly does not operate or meet performance
standards. 1-hour soft lockout. Clears after circula
tor successfully starts.
E 294 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.
E 295 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 satisfied.
E 310 Discharge error temperature sensor failure. Only shown if shorted or
out of range.
Compare outdoor sensor resistance to temperature/
resistance charts in installation instructions. Re
place sensor if necessary. Cleared in Communicat
ing mode: 30 seconds after fault recovered. In Non-
Communicating mode: Cleared after the current
heat call is completed.
E 311 Heat rate reduced to match indoor blower air flow. Warning Only. Furnace blower in cutback mode due
to restricted airflow. Reduce firing rate every 60
seconds to match available CFM. Check filter and
duct system. To clear, replace filter if needed or re
pair/add duct. 2-stage controls will reduce firing rate
to 1st stage. Clears when heat call finishes success
fully.

Page 13
TABLE 5 Continued
Code Diagnostic Codes/Status of Equipment Action Required to Clear and Recover
E 312 Restricted air flow in cooling or continuous fan mode is lower than cfm
setting.
Warning Only. Restricted airflow - Indoor blower is
running at a reduced CFM (Cutback Mode - The
variable speed motor has pre-set speed and
torque limiters to protect the motor from damage
caused by operating outside of design parameters
(0 to 0.8” W.C.. total external static pressure).
Check filter and duct system. To clear, replace
filter if needed or repair/add duct. Cleared after the
current service demand is satisfied.
E 313 Indoor or outdoor unit capacity mismatch. Communication only. Incorrect indoor/outdoor capacity code selected.
Check for proper configuring in installation instruc
tions. Alarm is just a warning. The system will op
erate, but might not meet efficiency and capacity
parameters. Alarm will clear when commissioning
is exited. Cleared after commissioning is com
plete.
E 331 Global network connection - Communication link problem. For Future Use.
E 334 Relay “Y1” stuck on interated control. Replace integrated control.
E 347 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.
E 348 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 in
put back to IFC chip). Critical Alert. Cleared after
reset and Y1 input sensed.
E 349 No 24 Volts between R & O on ”integrated control” with non communi
cating outdoor unit (Dual fuel module required for heat pump applica
tion).
Configuration link R to O needs to be restored.
Replace link or hard-wire. Applicable in non com
municating mode. Critical Alert.
E 370 Interlock switch sensed open for 2 minutes. Control sees the loss of 24VAC for 2 minutes .Ter
minate all services and wait for interlock switch to
close. The alarm will clear when 24VAC is continu
ously sensed on DS terminal for a minimum of 10
seconds or on a power reset.
E 400 LSOM - Compressor internal overload tripped. Thermostat demand Y1 is present; but, compres
sor is not running. Check power to outdoor unit.
Clears the error after current is sensed in both
RUN and START sensors for at least 2 seconds,
or after service is removed, or after power reset.
E 401 LSOM Compressor long run cycle or low system pressure. Compressor ran more than 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.
E 402 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.
E 403 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 con
secutive normal run cycles or power reset.
E 404 LSOM - Compressor rotor locked. Compressor short-cycling. (Running
less than 4 minutes).
Compressor rotor locked up due to run capacitor
short, bearings are seized, excessive liquid refrig
erant, etc. Clears the error after 4 consecutive nor
mal run cycles or after power reset.
E 405 LSOM - Compressor open circuit. Compressor circuit open (due to power disconnec
tion, open fuse, etc.) Clears the error after 1 nor
mal compressor run cycle.

Page 14
TABLE 5 Continued
Code Diagnostic Codes/Status of Equipment Action Required to Clear and Recover
E 406 LSOM - Compressor open start circuit. Required amount of current is not passing through
Start current transformer. Clears the error after cur
rent is sensed in START sensor, or after power re
set.
E 407 LSOM - Compressor open run circuit. Required amount of current is not passing through
Run current transformer. Clears the error after cur
rent is sensed in RUN sensor, or 1 normal compres
sor run cycle, or after power reset.
E 408 LSOM - Compressor contactor is welded. Compressor runs continuously. Clears the error
after 1 normal compressor run cycle or after power
reset.
E 409 LSOM - Compressor low voltage. Secondary voltage is below 18VAC. After 10 min
utes, operation is discontinued. Clears the code
after voltage is higher than 20 VAC for 2 seconds or
after power reset.
DIP Switch Settings
NOTE - All icomforttsettings are set at the icomfort Wi-Fi®
thermostat. See icomforttinstallation instruction. In icom
forttcommunication system all DIP switch and clippable
link settings are ignored. For conventional thermostats pro
ceed with DIP switch and clippable link settings as outlined
in the following.
Heating Operation DIP Switch Settings
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.
a - Select “OFF” for two-stage heating operation con
trolled by a two-stage heating thermostat (factory set
ting);
b - Select “ON” for two-stage heating operation con
trolled by a single-stage heating thermostat. This set
ting provides a timed delay before second-stage heat
is initiated.
Switch 2 -- Second Stage Delay (Used with Single-
Stage Thermostat Only) -- This switch is used to deter
mine the second stage on delay when a single-stage ther
mostat is being used. The switch is factory-set in the OFF
position, which provides a 7-minute delay before second-
stage heat is initiated. If the switch is toggled to the ON
position, it will provide a 12-minute delay before second-
stage heat is initiated. This switch is only activated when
the thermostat selector jumper is positioned for SINGLE-
stage thermostat use.
Switches 3 and 4 -- Blower-Off Delay -- The blower-on
delay of 30 seconds is not adjustable. The blower-off delay
(time that the blower operates after the heating demand
has been satisfied) can be adjusted by moving switches 3
and 4 on the integrated control. The unit is shipped from the
factory with a blower-off delay of 90 seconds. The blower
off delay affects comfort and is adjustable to satisfy individ
ual applications. Adjust the blower off delay to achieve a
supply air temperature between 90° and 110°F at the exact
moment that the blower is de-energized. Longer off delay
settings provide lower supply air temperatures; shorter set
tings provide higher supply air temperatures.Table 6 pro
vides the blower off timings that will result from different
switch settings.
TABLE 6
Blower Off Delay Switch Settings
Blower Off Delay
(Seconds) Switch 3 Switch 4
60 On Off
90 (Factory) Off Off
120 Off On
180 On On
Indoor Blower Operation DIP Switch Settings
Switches 5 and 6 -- Cooling Mode Blower Speed -- The
unit is shipped from the factory with the dip switches posi
tioned for high speed (4) indoor blower motor operation
during the cooling mode. Table 7 provides the cooling
mode blower speeds that will result from different switch
settings. Switches 5 and 6 set the blower cfm for second-
stage cool. The integrated control automatically ramps
down to 70% of the second-stage cfm for first-stage cfm.
Refer to blower tables for corresponding cfm values.
TABLE 7
Cooling Mode Blower Speeds
Speed Switch 5 Switch 6
Low On On
Medium Low Off On
Medium High On Off
High (Factory) Off Off
Switches 7 and 8 -- Cooling Blower Speed Adjustment
-- 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

Page 15
-10% to better suit the application. Table 8 below provides
blower speed adjustments that will result from different
switch settings. Refer to blower tables for corresponding
cfm values.
TABLE 8
Cooling Blower Speed Adjustment
Adjustment Switch 7 Switch 8
+10% (approx.) On Off
Factory Default Off Off
-10% (approx.) Off On
Switches 9 and 10 -- Cooling Mode Blower Speed
Ramping -- Blower speed ramping may be used to en
hance dehumidification performance. The switches are
factory set at option A which has the greatest effect on de-
humidification performance. Table 9 provides the cooling
mode blower speed ramping options that will result from
different switch settings. The cooling mode blower speed
ramping options are detailed below.
NOTE - The off portion of the selected ramp profile also ap
plies during heat pump operation in dual fuel applications.
TABLE 9
Cooling Mode Blower Speed Ramping
Ramping Option Switch 9 Switch 10
A (Factory) Off Off
B Off On
C On Off
D On On
Ramping Option A (Factory Selection)
Motor runs at 50% for 30 seconds.
Motor then runs at 82% for approximately 7-1/2 minu
tes.
If demand has not been satisfied after 7-1/2 minutes,
motor runs at 100% until demand is satisfied.
Once demand is met, motor runs at 50% for 30 sec
onds 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 satisfied after 7-1/2 minutes,
motor runs at 100% until demand is satisfied.
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 satisfied.
Once demand is met, motor runs at 100% for 45 sec
onds 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 satisfied.
Once demand is met, motor ramps down to stop.
OFFOFF 100% CFM
COMPRESSOR
DEMAND
Switches 11, 12 and 13 -- Heating Mode Blower Speed --
The switches are factory set to the OFF position which pro
vides factory default heat speed. Refer to table 10 for
switches 11, 12 and 13 that provided the corresponding in
creases or decrease to both high and low heat demand.
TABLE 10
Heating Mode Blower Speeds
Heat Speed Switch
11
Switch
12
Switch
13
Increase 24% On On On
Increase 18% On On Off
Increase 12% On Off On
Increase 6% On Off Off
Factory Default Off Off Off
Decrease 6% Off Off On
Decrease 12% Off On Off
Decrease18% Off On On
Switches 14 and 15 -- Continuous Blower Speed --
Table 11 provides continuous blower speed adjustments
that will result from different switch settings.
TABLE 11
Continuous Blower Speed
Continuous
Blower Speed Switch 14 Switch 15
28% of High Cool Speed Off On
38% of High Cool Speed
(Factory) Off Off
70% of High Cool Speed On Off
100% of High Cool Speed On On

Page 16
BLOWER DATA
SL280DF070V36A BLOWER PERFORMANCE (less lter)
0 through 0.8 in. w.g. (Heating) and 0 through 1.0 in. w.g. (Cooling) External Static Pressure Range
HEATING
1 Heating Speed
DIP Switch
Settings
First Stage Heating Speed - cfm Second Stage Heating Speed - cfm
+24% 1065 1170
+18% 1010 1115
+12% 960 1055
+6% 910 1000
Factory Default 860 945
–6% 805 885
–12% 755 830
–18% 705 775
COOLING
1 Cooling Speed
DIP Switch
Settings
First Stage Cooling Speed - cfm Second Stage Cooling Speed - cfm
Low Medium-Low Medium-High 2 High Low Medium-Low Medium-High 2 High
[phone] 1100 1240 1425 1515
Factory Default 665 780 925 985 1015 1115 1305 1380
–590 690 815 865 900 1025 1170 1250
1 Cooling and heating speeds are based on a combination of DIP switch settings on the furnace control. Refer to Installation Instructions for specic DIP Switch
Settings.
2Factory default setting.
NOTES - The effect of static pressure is included in air volumes shown.
First stage HEAT is approximately 91% of the same second stage HEAT.
First stage COOL (two-stage air conditioning units only) is approximately 70% of the same second stage COOL speed position.
Continuous Fan Only speed is selectable at 28%, 38%, 70% and 100% of the selected second stage cooling speed - minimum 250 cfm.
Lennox Harmony III™ Zone Control Applications - Minimum blower speed is 250 cfm.
SL280DF070V36A BLOWER MOTOR WATTS (COOLING)
1 Cooling Speed
DIP Switch
Settings
Motor Watts @ Various External Static Pressures - in. wg.
First Stage Second Stage
00.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 00.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
+ Setting
Cooling
Speed
Low 46 63 83 96 115 128 144 170 181 138 162 177 212 229 247 270 288 320 342 363
Med-low 66 81 104 127 144 160 175 195 219 185 210 238 266 293 317 349 374 399 432 448
Med-High 100 123 138 167 191 211 234 255 271 299 328 354 380 412 434 477 499 528 557 570
High 124 146 170 192 214 226 255 273 307 376 378 414 458 493 507 558 571 604 613 585
Factory Default
Cooling
Speed
Low 38 57 64 85 98 107 133 147 158 104 125 144 166 192 212 230 261 267 295 315
Med-low 49 72 87 96 122 135 160 176 197 141 167 184 216 237 256 288 304 326 356 383
Med-High 70 90 109 132 158 172 201 222 231 218 245 276 306 323 357 374 403 444 472 489
High 90 108 138 154 170 192 223 235 260 259 280 317 350 381 405 449 469 496 532 544
– Setting
Cooling
Speed
Low 33 45 60 73 89 104 114 123 144 73 89 111 124 155 175 196 210 224 243 263
Med-low 40 54 74 86 106 115 134 142 170 108 118 153 170 196 219 227 253 266 286 316
Med-High 52 74 85 107 128 149 161 181 201 156 181 208 222 253 284 305 333 356 374 398
High 64 82 98 129 139 157 183 197 214 176 198 228 267 283 317 355 382 396 425 450

Page 17
BLOWER DATA
SL280DF090V48B BLOWER PERFORMANCE (less lter)
0 through 0.8 in. w.g. (Heating) and 0 through 1.0 in. w.g. (Cooling) External Static Pressure Range
HEATING
1 Heating Speed
DIP Switch
Settings
First Stage Heating Speed - cfm Second Stage Heating Speed - cfm
+24% 1360 1500
+18% 1285 1415
+12% 1220 1350
+6% 1135 1285
Factory Default 1075 1200
–6% 1030 1110
–12% 960 1050
–18% 890 975
COOLING
1 Cooling Speed
DIP Switch
Settings
First Stage Cooling Speed - cfm Second Stage Cooling Speed - cfm
Low Medium-Low Medium-High 2 High Low Medium-Low Medium-High 2 High
[phone] 1085 1330 1545 1730
Factory Default 690 820 950 1110 990 1200 1400 1,595
–610 745 855 1005 895 1075 1270 1460
1 Cooling and heating speeds are based on a combination of DIP switch settings on the furnace control. Refer to Installation Instructions for specic DIP Switch
Settings.
2Factory default setting.
NOTES - The effect of static pressure is included in air volumes shown.
First stage HEAT is approximately 91% of the same second stage HEAT.
First stage COOL (two-stage air conditioning units only) is approximately 70% of the same second stage COOL speed position.
Continuous Fan Only speed is selectable at 28%, 38%, 70% and 100% of the selected second stage cooling speed - minimum 380 cfm.
Lennox Harmony III™ Zone Control Applications - Minimum blower speed is 380 cfm.
SL280DF090V48B BLOWER MOTOR WATTS (COOLING)
1 Cooling Speed
DIP Switch
Settings
Motor Watts @ Various External Static Pressures - in. wg.
First Stage Second Stage
00.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 00.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
+ Setting
Cooling
Speed
Low 33 59 77 98 122 142 166 192 214 97 129 150 188 217 247 267 302 323 365 394
Med-low 64 91 118 139 167 193 215 246 272 156 188 230 269 313 346 377 429 452 491 529
Med-High 92 119 150 174 209 240 261 292 319 281 304 361 413 455 473 528 552 607 637 673
High 136 174 200 236 264 305 342 376 399 442 470 538 566 603 636 691 730 775 814 838
Factory Default
Cooling
Speed
Low 23 50 63 84 104 124 150 168 194 74 103 126 155 183 210 243 264 290 316 349
Med-low 45 74 98 114 140 163 192 216 247 120 155 192 223 246 276 314 352 382 412 458
Med-High 62 93 122 143 173 195 232 260 290 206 236 285 324 369 401 437 483 514 551 590
High 112 142 168 202 220 253 282 306 346 323 336 400 445 489 523 558 595 643 660 689
– Setting
Cooling
Speed
Low 17 38 56 72 88 115 132 150 170 51 78 106 129 155 178 207 229 259 289 311
Med-low 31 54 76 97 117 142 165 187 209 92 122 147 178 217 244 264 289 322 361 385
Med-High 51 76 104 125 153 175 202 222 258 135 177 208 233 272 311 349 386 417 452 491
High 78 107 137 155 184 215 246 268 301 247 282 313 365 398 445 483 521 558 582 620

Page 18
BLOWER DATA
SL280DF090V60C BLOWER PERFORMANCE (less lter)
0 through 0.8 in. w.g. (Heating) and 0 through 1.0 in. w.g. (Cooling) External Static Pressure Range
HEATING
1 Heating Speed
DIP Switch
Settings
First Stage Heating Speed - cfm Second Stage Heating Speed - cfm
+24% 1540 1695
+18% 1465 1615
+12% 1390 1530
+6% 1320 1450
Factory Default 1245 1365
–6% 1170 1285
–12% 1095 1205
–18% 1020 1120
COOLING
1 Cooling Speed
DIP Switch
Settings
First Stage Cooling Speed - cfm Second Stage Cooling Speed - cfm
Low Medium-Low Medium-High 2 High Low Medium-Low Medium-High 2 High
[phone] 1590 1585 1770 2000 2275
Factory Default 1020 1135 1285 1445 1420 1610 1845 2,050
–900 1005 1155 1280 1305 1395 1645 1875
1 Cooling and heating speeds are based on a combination of DIP switch settings on the furnace control. Refer to Installation Instructions for specic DIP Switch
Settings.
2Factory default setting.
NOTES - The effect of static pressure is included in air volumes shown.
First stage HEAT is approximately 91% of the same second stage HEAT.
First stage COOL (two-stage air conditioning units only) is approximately 70% of the same second stage COOL speed position.
Continuous Fan Only speed is selectable at 28%, 38%, 70% and 100% of the selected second stage cooling speed - minimum 450 cfm.
Lennox Harmony III™ Zone Control Applications - Minimum blower speed is 450 cfm.
SL280DF090V60C BLOWER MOTOR WATTS (COOLING)
1 Cooling Speed
DIP Switch
Settings
Motor Watts @ Various External Static Pressures - in. wg.
First Stage Second Stage
00.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 00.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
+ Setting
Cooling
Speed
Low 81 109 135 154 190 215 243 269 291 197 229 269 314 351 403 424 465 503 542 572
Med-low 117 142 175 204 227 252 285 308 340 299 329 388 432 466 495 549 586 645 669 705
Med-High 143 183 208 247 283 312 352 385 423 451 501 521 587 633 664 705 765 794 848 879
High 209 246 291 329 370 402 447 490 525 689 720 783 826 890 938 995 1032 1072 1104 1131
Factory Default
Cooling
Speed
Low 63 92 114 139 162 186 216 242 270 144 183 217 248 286 307 354 386 421 459 498
Med-low 82 111 141 159 195 223 247 274 308 211 245 294 331 369 401 445 486 523 559 604
Med-High 121 148 181 211 241 279 304 331 356 331 366 411 468 497 546 588 629 664 707 748
High 155 194 216 260 296 334 363 393 434 481 535 574 604 655 714 762 816 851 877 942
– Setting
Cooling
Speed
Low 53 76 101 121 139 166 184 209 238 117 149 180 203 235 269 294 327 349 387 421
Med-low 68 94 120 137 166 193 219 239 266 154 187 219 258 291 319 365 386 424 458 492
Med-High 88 117 144 169 204 227 251 282 313 225 254 298 355 382 427 459 503 542 580 604
High 124 156 183 208 239 267 304 326 359 362 395 436 484 520 568 614 643 686 721 746

Page 19
BLOWER DATA
SL280DF110V60C BLOWER PERFORMANCE (less lter)
0 through 0.8 in. w.g. (Heating) and 0 through 1.0 in. w.g. (Cooling) External Static Pressure Range
HEATING
1 Heating Speed
DIP Switch
Settings
First Stage Heating Speed - cfm Second Stage Heating Speed - cfm
+24% 1645 1810
+18% 1565 1720
+12% 1485 1635
+6% 1405 1545
Factory Default 1325 1460
–6% 1245 1370
–12% 1170 1285
–18% 1090 1195
COOLING
1 Cooling Speed
DIP Switch
Settings
First Stage Cooling Speed - cfm Second Stage Cooling Speed - cfm
Low Medium-Low Medium-High 2 High Low Medium-Low Medium-High 2 High
[phone] 1525 1500 1755 1915 2120
Factory Default 975 1115 1250 1400 1360 1585 1770 1960
–895 1005 11301245 1225 1405 1595 1760
1 Cooling and heating speeds are based on a combination of DIP switch settings on the furnace control. Refer to Installation Instructions for specic DIP Switch
Settings.
2Factory default setting.
NOTES - The effect of static pressure is included in air volumes shown.
First stage HEAT is approximately 91% of the same second stage HEAT.
First stage COOL (two-stage air conditioning units only) is approximately 70% of the same second stage COOL speed position.
Continuous Fan Only speed is selectable at 28%, 38%, 70% and 100% of the selected second stage cooling speed - minimum 450 cfm.
Lennox Harmony III™ Zone Control Applications - Minimum blower speed is 450 cfm.
SL280DF110V60C BLOWER MOTOR WATTS (COOLING)
1 Cooling Speed
DIP Switch
Settings
Motor Watts @ Various External Static Pressures - in. wg.
First Stage Second Stage
00.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 00.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0
+ Setting
Cooling
Speed
Low 78 101 128 144 172 200 218 244 264 172 196 243 284 321 360 391 428 452 494 528
Med-low 108 135 162 192 213 241 269 295 324 268 294 352 376 424 466 505 554 581 604 645
Med-High 146 180 203 238 271 305 334 358 396 373 424 459 504 529 575 641 680 712 747 810
High 181 219 254 291 327 365 401 436 479 510 557 596 660 725 763 815 869 922 962 993
Factory Default
Cooling
Speed
Low 62 87 108 125 148 173 196 222 239 135 165 194 231 267 305 320 346 381 422 457
Med-low 87 115 135 158 189 218 236 264 285 195 226 270 311 347 377 421 455 494 530 562
Med-High 114 140 173 201 224 250 283 312 339 290 335 358 401 450 497 528 565 611 640 677
High 148 186 207 246 282 307 354 375 410 395 438 484 525 559 608 659 711 745 776 826
– Setting
Cooling
Speed
Low 47 67 94 108 128 140 172 193 212 106 134 161 191 214 238 259 295 322 349 379
Med-low 67 91 114 134 151 180 206 226 247 147 181 210 245 280 312 347 376 404 445 476
Med-High 94 116 141 167 198 210 242 259 288 207 236 284 320 356 391 421 473 494 535 573
High 118 146 176 202 222 248 285 313 337 280 315 356 398 444 478 520 559 607 627 669

Page 20
On-Board Links
Note: In icomforttsystems with a conventional outdoor
unit (non-communicating), the on-board clippable links
must be set to properly configure the system.
WARNING
Carefully review all configuration information pro
vided. Failure to properly set DIP switches, jumpers
and on-board links can result in improper operation!
On-Board Link W914 Dehum or Harmony (R to DS)
On-board link W914, is a clippable connection between ter
minals R and DS on the integrated control. W914 must be
cut when the furnace is installed with either the Harmony
IIIzone control or a thermostat which features humidity
control. If the link is left intact the PMW signal from the Har
mony III control will be blocked and also lead to control
damage. Refer to table 12 for operation sequence in ap
plications including SL280DFV, a thermostat which fea
tures humidity control and a single-speed outdoor unit.
Table 13 gives the operation sequence in applications with
a two-speed outdoor unit.
On-Board Link W951 Heat Pump (R to O)
On-board link W951 is a clippable connection between ter
minals 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 ener
gized eliminating the HEAT MODE in the heat pump.
On-Board Link W915 2 Stage Compr (Y1 to Y2)
On-board link W915 is a clippable connection between ter
minals Y1 and Y2 on the integrated control. W915 must be
cut if two-stage cooling will be used. If the Y1 to Y2 link is
not cut the outdoor unit will operate in second-stage cool
ing only.
TABLE 12
SL280DFV, Non-Communicating Thermostat with Humidity Control Feature and Single-Stage Outdoor Unit
OPERATING
SEQUENCE SYSTEM DEMAND SYSTEM RESPONSE
System
Condition Step
Thermostat Demand Relative Humidity
Compres
sor
Blower
CFM
(COOL)
Comments
Y1 O G W
1Status D
NO CALL FOR DEHUMIDIFICATION
Normal Operation 1 On On On Acceptable 24
VAC High 100%
Compressor and indoor
blower follow thermostat
demand
BASIC MODE (only active on a Y1 thermostat demand)
Normal Operation 1 On On On Acceptable 24
VAC High 100% ComfortSense®7000 ther
mostat energizes Y1 and
de-energizes D on a call
for de-humidification
Dehumidification
Call 2 On On On Demand 0 VAC High 60%, 65%, 70%*
PRECISION MODE (operates independent of a Y1 thermostat demand)
Normal Operation 1 On On On Acceptable 24
VAC High 100% Dehumidification mode be
gins when humidity is
greater than set point
Dehumidification call 2 On On On Demand 0
VAC High 60%, 65%, 70%*
Dehumidification call
ONLY 1 On On On Demand 0 VAC High 60%, 65%, 70%*
ComfortSense®7000 ther
mostat will try to maintain
room humidity setpoint by
allowing the room space to
maintain a cooler room
thermostat setpoint**
Jumpers at indoor unit with a single stage outdoor unit
With Condensing unit - Cut W914 (R to DS) on SureLight®board
With Heat Pump - Cut W914 (R to DS) & W951 (R to O) on SureLight®board
ComfortSense®7000 thermostat to use for this application - Y2081 4 heat / 2 cool
*Dehumidification blower speed is 70% of COOL speed for all units .
**In Precision mode, ComfortSense®7000 thermostat will maintain room temperature up to 2 °F (1.2°C) cooler than room
setting.