Lennox 10T50 Assembly instructions

507240-03
1/2018
Supersedes 6/2017
iComfort®Equipment
Interface Module
Installation and Setup
Guide
(10T50)

2
Shipping and Packing List.................................................................2
Application and Requirements..........................................................2
Indoor Transformer Requirements................................................... 2
Equipment ....................................................................................... 2
Installation...........................................................................................5
Conguration Setup...........................................................................5
EIM, 24VAC Furnace and iComfort Heat Pump .............................. 5
EIM, iComfort Furnace and 24VAC Heat Pump .............................. 5
Unit Type Jumpers........................................................................... 6
Heat Stage Jumper Positions .......................................................... 6
Air Temperature Sensor Connections.............................................. 6
iComfort Terminal Connections ....................................................... 6
Heat Stage Jumpers........................................................................ 7
Dual-Fuel Terminal Connections ..................................................... 7
Conventional Terminal Connections................................................ 8
LED Indicators ................................................................................. 8
Soft Disable ..................................................................................... 8
iComfort Wi-Fi Commissioning (Conventional Outdoor Unit) .......... 9
iComfort S30 Commissioning (Conventional Outdoor Unit) ............ 9
Operating Environment Specications ............................................9
Unit Dimensions ...............................................................................10
Duel-Fuel Operations .......................................................................10
Field Wiring ....................................................................................... 11
Alert Codes and Troubleshooting...................................................17
WARNING
This product contains a chemical known to the State of California to
cause cancer, birth defects, or other reproductive harm.
TABLE OF CONTENTS Shipping and Packing List
Quantity Description
1 iComfort® Equipment Interface Module.
1 Installation and setup guide
1Warranty certicate
WARNING
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) or a service agency.
Application and Requirements
Indoor Transformer Requirements
The following tTable 1 lists the required indoor unit transformer rating (VA)
for specic congurations.
Table 1. System VA Loading Chart
Conguration Minimum Transformer Rating
(VA)
2-Stage HP, 3-Stage Electric heat 70
2-Stage HP, 2-Stage Furnace (with tempering) 70
2-Stage HP, 2-Stage Furnace (without tempering) 50
2-Stage AC, 2-Stage Furnace 40
Equipment
The Equipment Interface Module (EIM) is used with an iComfort series
thermostat (iComfort Wi-FI®or iComfort®S30) using the R, i+, i-, and C
terminals. The EIM is the interface between conventional (non-iComfort)
HVAC equipment and iComfort HVAC equipment. The control supports the
following equipment applications:
NOTE: EIM will support single-stage outdoor units with single-stage or
variable-stage indoor furnaces.

3
OUTDOOR AIR SENSOR
CONNECTIONS
DISCHARGE AIR
SENSOR CONNECTIONS
ICOMFORT
®
CONNECTIONS
NON-COMMUNICATING TERMINALS
STATUS LED
COMMUNICATION INDICATOR
LED
DUAL-FUEL
CONNECTIONS
UNIT TYPE JUMPER
TERMINALS
HEAT STAGES
JUMPER TERMIINALS HEAT PUMP CAPACITY
JUMPER TERMINALS
3 AMP FUSE
Figure 1. Terminals and LEDs

4
tions, additional components
may need to be added, see figure
5 on page 8.
iComfort Series
Thermostat
Equipment Interface
Model (EIM)
24VAC Air Handler or
Furnace (Indoor Unit)
iComfort-enabled
Air Conditioner or
Heat Pump
(Outdoor Unit)
Wiring Legend
4−wire communicating
24VAC conventional
EIM with Air Hander or Furnace (Indoor Unit)
and either a Air Conditioner or Heat Pump
(Outdoor Unit)
24VAC Air
Conditioner
or Heat Pump
(Outdoor Unit)
ICOMFORT
WI-FI
ICOMFORT
S30
Figure 2. System View

5
Installation
WARNING
Controls in this module are sensitive to moisture. Do NOT secure this
module to the sheet metal cabinet where moisture may condense during
periods of high humidity. Secure the module to a nearby wooden stud, if
possible.
IMPORTANT
The iComfort series thermostat paired with the Equipment Interface
Module (EIM) will work with most 24VAC furnaces, air handlers, air
conditioners and heat pumps (up to 2-stages of cooling and 3-stages of
heat).
The iComfort series thermostat without the Equipment Interface Module
(EIM) will work with Lennox branded communicating HVAC equipment.
1. Remove the module cover.
2. Mount the Equipment Interface Module (EIM) near the indoor unit.
3. Use the wiring diagrams reference in Table 10 on page 11 to complete
the wiring connections for the specic application and conguration.
CAUTION
Electrostatic discharge can affect electronic components.Take precautions
during unit installation and service to protect the unit’s electronic controls.
Precautions will help to avoid control exposure to electrostatic discharge
by putting the unit, the control and the technician at the same electrostatic
potential. Neutralize electrostatic charge by touching hand and all tools
on an unpainted unit surface before performing any service procedure
Conguration Setup
How the EIM is congured is determined by the system components.
NOTE: Changing jumper positions after the control has been powered-up
requires recommissioning for the change to be recognized.
NOTE: When the Equipment Interface Module is replaced,
recommissioning the iComfort series thermostat will also need to
be re-accomplished. See the iComfort series thermostat Setup
Guide for recommissioning procedure.
EIM, 24VAC Furnace and iComfort Heat Pump
1. Set the EIM Unit Type Jumper to IFC.
2. Set the EIM Heat Stage Jumper to the applicable number of furnace
heat stages.
3. Use the iComfort series thermostat to complete the commissioning
procedure.
EIM, iComfort Furnace and 24VAC Heat Pump
1. Set the EIM Unit Type Jumper to Heat Pump.
2. Set the EIM Heat Stage Jumper to the applicable number of heat pump
heating stages.
3. Wire according to gure 10.
4. Use the iComfort series thermostat to complete the commissioning
procedure.
NOTE: For two-stage heat pump go to the heat pump outdoor control,
locate J2 - 2ND STAGE LOCKIN and disable this function by
removing the installed jumper and relocating it to one pin only.

6
Unit Type Jumpers
Set the unit type jumper for the type of indoor unit being used (see gure
2 and table 4). The factory default setting is IFC. If jumper is missing from
header, alarm 130 is activated.
Table 2. Unit Type Jumpers Positions
Jumper
Position Indoor Unit Outdoor Unit
HP iComfort Furnace Conventional Heat Pump
IFC Conventional Furnace Conventional Heat Pump or air
conditioner
AHC Conventional Air Handler
HP IFC AHC
Figure 3. Unit Type Jumper Positions
Table 3. Unit Type Jumpers Positions
Label Function / Description
HP Equipment Interface Module—Heat Pump
IFC Equipment Interface Module—Furnace (factory default)
AHC Equipment Interface Module—Air Handler
Heat Stage Jumper Positions
The heating staging Jumper must be set for the number of stages of electric
heat (air handler) or the number of stage of gas heat (furnace) and stages
of heat pump. Using the heat stages jumper (see gure 3 and table 8).
The factory default setting is position 2. If jumper is missing from header,
alarm 130 is activated.
0 1 2 3
Figure 4. Heat Stage Jumper Positions
24VAC Heat Pump Size Setting
Heat pump size must be congured when using a non-communicating heat
pump using the Heat Pump Size jumper (see gure 4 and table 5). Factory
default setting is for 3.0 (3-ton). If jumper is missing from header, alarm 130
is activated.
1.
5
2.
0
2.
5
3.
0
3.
5
4.
0
5.
0
Figure 5. Conventional Heap Pump Capacity Jumper Setting
Air Temperature Sensor Connections
Refer to “Figure 1. Terminals and LEDs” on page 3 for various terminal
locations.
Table 4. Unit Type Jumpers Positions
Label Function / Description
Outdoor Air
Sensor
Show ambient temperatures (optional if weather feed is acceptable or
outdoor unit is a communicating unit; use X2658 Outdoor Sensor - 2 ter-
minals).
NOTE: Wiring distance between the EIM and the outdoor temperature
sensor can not exceed 150 feet (45 meters) when wired with
minimum 22AWG (Recommend) 18AWG dedicated two-
conductor thermostat cable.
Discharge Air
Sensor
Optional for diagnostics of indoor air; use 88K38 Discharge Air Sensor - 2
terminals.
iComfort Terminal Connections
Table 5. Unit Type Jumpers Positions
Label Function / Description
R 24VAC communication power Input
i+ Communication high – data line
i- Communication low – data line
C 24VAC communication common power Input

7
Heat Stage Jumpers
Use the following table to set the heat stage jumpers.
Table 6. Heat Stage Jumpers
Label
(Position)
Air Handler Heat
Stages Furnace Heat Stages Heat Pump Stages
Number of
Electric Heat
Stages
Stage
Percentage
Number of
Gas Stages
Stage
Percentage
Number of
Compressors
Stages
Stage
Percentage
0No Electric
Heat 0 1 100% 1 100%
1 1 100% 1 100% 1 100%
2
(default) 250%, 100% 270%. 100% 370%. 100%
3 3
33.5%,
66.5%,
100%
270%,
100% 370%. 100%
NOTE: If jumper is missing, setting defaults to single stage. Changing jumper position
after power-up requires recommission for the change to be recognized.
Dual-Fuel Terminal Connections
Table 7. Dual-Fuel Terminals
Label Description Function
DFTS Pre-coil discharge air tem-
perature (2 terminals)
The pre-coil discharge air sensor should
be installed downstream of the gas heat
exchanger and before the in door coil when
a heat pump is used and defrost tempering
is required.
It must be placed in free airow, where
other accessories (such as humidiers,
UV lights, etc.) will not interfere with its ac-
curacy. Wiring distance between the EIM
and the discharge air sensor should not
exceed 10 feet when using 18AWG ther-
mostat wire.
W1-DEF Defrost signal input
This input is used in systems with non-com-
municating heat pumps for defrost indica-
tion. The input provides a nominal load of
50 mA, 24 VAC.
0Heat Pump Reversing Valve
(Powered for cooling)
In systems with communicating IFC,
the EIM (HP) O output is connected to a
non-communicating heat pump compatible
with O signal for reversing valve operation.
A 24VAC signal is generated on O for cool-
ing operation, while the terminal is open for
heating operation.
B
Heat Pump Reserving
Valve
(Powered for heating)
In systems with communicating IFC,
the EIM (HP) B output is connected to a
non-communicating heat pump compatible
with B signal for reversing valve operation.
A 24VAC signal is generated on B for heat
pump operation, while the terminal is open
for cooling operation.

8
Conventional Terminal Connections
Table 8. Conventional Terminals
Label Description Function
W1 1st - stage heat output (1st stage gas heat output when congured as IFC
and 1st stage electric heat output when congured as AHC.
W2 2nd - stage heat output (2nd stage gas heat output when congured as IFC
and 2nd stage electric heat output when congured as AHC.
W3 3rd - stage heat output (3nd stage electric heat output when congured as
AHC)
GIndoor blower control (continuous fan) (monitoring only). G input may be connected to IAQ devices such as LVCS, HRV or ERV to turn the indoor
blower on and off.
Y2 2nd - stage compressor output
Y1 1st - stage compressor output
DS 24VAC dehumidication signal output. The DS terminal is powered when
there is not a dehumidication call.
CClass II, 24VAC transformer
common
R and C terminals are used to receive
power from the indoor unit and capable
of providing the power to the EIM and all
the associated loads. The R power in-
put uses a 3A fuse (Lennox part number
25J4901.
RClass II. 24VAC transformer
power
H24VAC humidier signal output
OHeat pump reversing valve
(24VAC = cool)
Used as reversing valve output for heat
pumps. The EIM uses a single-pole dual
throw relay to generate O and B signals.
Normally the O output is open and B out-
put at 24VAC during heating calls. During
cooling calls O is 24VAC and B open. With
relay de-energized 24VAC is present on O
terminal.
When power off/ or control reset, 24VAC
power shall not be present on the O ter-
minal.
BHeat pump reversing valve
(24 VAC = heat)
LED Indicators
This control has two green LED to indicate status and communication
activity One LED is labeled Status and the other is labeled RSBUS.
RSBUS LED
The RSBus LED ashes when information is being communicated over the
RSBus.
Status LED
The following table lists all status LED information.
Table 9. Status LED (Green)
Green LED Function / Description
Steady On Remains steady ON until the device sends its start-up mes-
sage.
Blinks 3 second OFF and 1
second ON Soft disable state
Blinks 2 second ON and 2
second OFF
Service is being provided (W, Y or G relay is
ON, or G input ON
Blinks 1 second ON and 1
second OFF Alarm is present.
Soft Disable
Soft disabling is when the iComfort® thermostat nds an unknown control
such as a indoor or outdoor unit control, iHarmony®zoning system or
Equipment Interface Module (EIM) on the system communication bus. The
thermostat sends the unknown control a message to go into soft disable
mode until component is properly congured.
The iComfort®thermostat will not show any code for a soft disabled control.
When soft disabling occurs only the control that has been disabled will
display the blinking LED status. In this case, the control blinks three
seconds OFF and one second ON.
Use the following procedure if the equipment interface module is displaying
the soft disable code.
1. Conrm proper wiring between all devices such as thermostat, EIM,
indoor and outdoor unit).
2. Cycle power to the control that is displaying the soft disable code.
3. Touch the Lennox icon on the thermostat home screen and hold until
the installer warning screen appears.
4. Touch yes to continue.
5. Touch Setup and then conrm to continue.
6. Use this Thermostat? Touch press here to continue.
7. Touch the next button to continue past the next three screens.
8. From the System Devices list, touch reset ALL to reset all devices.
9. Touch the conrm button.
The thermostat will reboot and start through the setup process again.

9
IMPORTANT
If any jumpers were set incorrectly AFTER commissioning was
completed, then reposition jumpers to correct positions. Re-running
the commissioning procedure will be required at the iComfort series
thermostat.
iComfort Wi-Fi Commissioning (Conventional Outdoor Unit)
Both unit capacity and number of compressor stages are required to be
congured through the iComfort series thermostat. Once the outdoor unit
has been installed and connected to the equipment interface module, go to
the thermostat and start the conguration process.
1. From the system devices screen, touch the yes button to add or
remove non-communicating equipment.
2. A non-communicating device list will appear, select Outdoor Unit
Type and then touch edit.
3. Under Outdoor Unit Type, select the applicable 1 or 2-stage unit.
Touch save to continue.
4. Under non-communicating device list, select Outdoor Unit Capacity
and then touch edit.
5. Touch either the up or down arrows to selected the applicable Outdoor
Unit Capacity. Valid options are 18, 24, 30, 36, 42, 48 and 60. Touch
save to continue.
This completes the conguring of the conventional outdoor unit.
iComfort S30 Commissioning (Conventional Outdoor Unit)
Both unit capacity and number of compressor stages are required to be
congured through the iComfort series thermostat. Once the outdoor unit
has been installed and connected to the equipment interface module, go to
the thermostat and start the conguration process.
1. From the equipment found screen, touch the non-communication
equipment location to add non-communicating equipment.
Figure 6. Adding Conventional Outdoor Unit
2. A add/remove equipment screen will appear. Under Outdoor Unit
Type, select the applicable 1 or 2-stage unit.
3. Touch either the plus or minus buttons to selected the applicable
Outdoor Unit Capacity. Valid options are 18, 24, 30, 36, 42, 48 and
60.
4. Touch save to continue.
Operating Environment Specications
The Equipment Interface Module is designed to operate in the following
environmental conditions.
• Operating Temperature Range: 40°F to 176°F (40° C to 80°C).
• Shipping and Storage Temperature Range: 40° F to 185°F (40°C to
85°C).
• Operating Humidity Range: 10% to 90% non-condensing at 104°F.

10
Unit Dimensions
8” (203mm)
6” (152mm)
1-5/8” (42mm)
Figure 7. Unit Dimensions
Duel-Fuel Operations
To use the EIM in dual-fuel mode, the following equipment combinations
and conguration is required.
Defrost Air Tempering Kit (67M41) will be required. The included DT1
discharge temperature probe is inserted in the furnace air outlet between
the furnace and the indoor coil to keep the furnace from overheating the
coil which would cause heat pump high pressure tripping during the defrost
cycling. The DT1 is only needed with non-communicating furnaces and is
not required for air handlers.
Wiring example for the DT1 Discharge Temperature Probe is in “Figure 14.
Dual-Fuel - Conventional Furnace with Conventional Heat Pump” on page
12.
iComfort Series
Thermostat
Equipment Interface
Model (EIM)Furnace
24VAC conventional
DUAL−FUEL WITH DEFROST TEMPERING
(EIM, 24VAC Furnace and Communicating Heat Pump)
iComfort-enabled
Heat Pump
(Outdoor Unit)
Outdoor Sensor
(Included with
Heat Pump)
Defrost Tempering
(Available only if
furnace is variable
Optional
NOTE: iComfort Wi-Fi
Thermostat with firmware
version 2.1 or higher)
capacity
or multi-stage)
Wiring Legend
4-wire communicating
ICOMFORT
WI-FI
ICOMFORT
S30
Figure 8. EIM, Conventional Furnace and iComfort Heat Pump

11
iComfort Series
Thermostat iComfort-enabled
Furnace
Wiring Legend 4-wire communicating
24VAC conventional
DUAL−FUEL WITH DEFROST TEMPERING
(EIM, Communicating Furnace and 24VAC Heat Pump
24VAC
Conventional Heat
Pump
(Outdoor Unit)
X2658 Outdoor
Sensor Required
Equipment Interface
Model (EIM)
NOTE: iComfort Wi-Fi
Thermostat with firmware
version 2.1 or higher)
ICOMFORT
WI-FI
ICOMFORT
S30
Figure 9. EIM, Conventional Furnace and Conventional Heat Pump
Field Wiring
Table 10. Wiring Diagrams
System Indoor
Unit
Outdoor
Unit Diagram
Air Conditioner Conventional Conventional Figure 10
Heat Pump Conventional Conventional Figure 11 on page 12
Dual Fuel Conventional iComfort Figure 12 on page 12
Dual Fuel iComfort Conventional Figure 13 on page 12
Dual Fuel Conventional Conventional Figure 14 on page 12
Dual Fuel with
iHarmony iComfort Conventional Figure 15 on page 13
Baseboard Heat Conventional* iComfort Figure 16 on page 14
Table 10. Wiring Diagrams
System Indoor
Unit
Outdoor
Unit Diagram
Hot Water Coil with
Aquastat Blower
Control
Conventional iComfort Figure 17 on page 14
Accessories - De-
humidiers, humidi-
ers, HEPA Bypass
Filter (HRV / ERV)
Conventional Not applicable Figure 18 on page 15
Accessories - EDA
Humiditrol and
LVCS Ventilation
Control
Conventional Conventional Figure 19 on page 16
* 24VAC conventional air handler or CBX32MV(-6) / CBX40UHV used as 24VAC conven-
tional.
REMOVE JUMPER BETWEEN R AND W2
IF PRESENT. IT MAY CAUSE
ERRONEOUS ALERT CODE 125.
ICOMFORT SERIES
THERMOSTAT
Figure 10. Conventional Furnace or Air Hander with Conventional Air Conditioner

12
REMOVE JUMPER BETWEEN R AND W2
IF PRESENT. IT MAY CAUSE
ERRONEOUS ALERT CODE 125.
ICOMFORT SERIES
THERMOSTAT
Figure 11. Conventional Air Hander with Conventional Heat Pump
IF THERE IS A JUMPER INST
ALLED
BETWEEN R AND W2 ON INDOOR UNI
T,
THEN REMOVED. IF NOT REMOVE IT
MA
Y CAUSE ERRONEOUS ALERT
CODE 125
.
REMOVE JUMPER BETWEEN R AND W2 IF
PRESENT. IT MAY CAUSE ERRONEOUS ALERT
CODE 125.
ICOMFORT SERIES
THERMOSTAT
Figure 12. Dual-Fuel - Conventional Furnace with iComfort Heat Pump or Air
Conditioner
ICOMFORT SERIES
THERMOSTAT
Figure 13. Dual-Fuel - iComfort Furnace with Conventional Heat Pump
REMOVE JUMPER BETWEEN R AND W2
IF PRESENT. IT MAY CAUSE
ERRONEOUS ALERT CODE 125.
ICOMFORT SERIES
THERMOSTAT
Figure 14. Dual-Fuel - Conventional Furnace with Conventional Heat Pump

13
ICOMFORT SERIES
THERMOSTAT
Figure 15. Dual-Fuel - iComfort Furnace, iHarmony Zoning with Conventional Heat Pump

14
ICOMFORT SERIES
THERMOSTAT
Figure 16. Baseboard Heat - Conventional Air Handler (CBX32MV(-6) or CBX40UHV) with either a iComfort Air Conditioner or Heat Pump
REMOVE JUMPER BETWEEN R AND W2
IF PRESENT. IT MAY CAUSE
ERRONEOUS ALERT CODE 125.
Figure 17. Hot Water Coil Heat with Aquastat Blower Control - Conventional Air Handler (CBX32MV(-6) or CBX40UHV)

15
REMOVE JUMPER
BETWEEN R AND
W2 IF PRESENT.
IT MAY CAUSE
ERRONEOUS ALERT
CODE 125.
ICOMFORT SERIES
THERMOSTAT
Figure 18. Optional Accessories with Conventional Outdoor Unit

16
REMOVE JUMPER BETWEEN R AND W2
IF PRESENT. IT MAY CAUSE
ERRONEOUS ALERT CODE 125.
ICOMFORT SERIES
THERMOSTAT
Figure 19. Optional Accessories with Conventional Indoor Unit

17
Alert Codes and Troubleshooting
Error codes are transmitted to the thermostat. No codes are stored in the EIM.
Table 11. Alert Codes and Troubleshooting
Alert Code Priority
Condition
Applicable System
Component(s)
Alert Text Component or System Operational State
and Troubleshooting Tip How to clear the alert code
10 Critical
All iComfort series
thermostats, air handler,
furnace, outdoor unit, EIM
and iHarmony.
The thermostat has
found an unknown de-
vice on the system.
The iComfort Series Thermostats when NOT in con guration mode
has detected an unknown device. Typically the thermostat will send a
command to the unknown device and place it in a soft disable state.
The soft disable control will indicate so as follows:
√ On air handler, furnace and outdoor controls, the state is displayed
by double horizontal lines on seven-segment display.
√ On the damper control module or equipment inter face equipment,
the green LED will blink three seconds on and one second off.
Cycling power to the soft disabled control may clear the condition. If
cycling power does not clear the soft disabled state then replace con-
trol.
Clear alert code by recon-
guring the system
12 Critical
All iComfort series
thermostats, furnace, EIM or
air handler
The thermostat cannot
nd an iComfort® in-
door unit
iComfort Series Thermostats did not nd an indoor unit. Make sure
there is an iComfort® indoor unit on the system.
√ Check R, i+, i- and C connections and voltages.
√ Ohm wires and cycle power.
√ Check for voltage and missing component.
√ Verify that equipment interface module is congured as air handler
or furnace when used with a non-communicating indoor unit.
√ Go to menu > advance settings > view dealer control center >
equipment and press reset all equipment. This will allow the system
to auto-detect any iComfort®components attached.
√ Replace indoor unit control if there is no response.
Automatically clears when
the system detects that the
issue no longer exists.
105 Critical
All iComfort series
thermostats, furnace, air
handler, outdoor unit, EIM or
iHarmony
A system component
has lost communication
with the system.
System component (device) is unable to communicate.
√ This may indicate the existence of other active alert codes.
√ In most cases errors are related to electrical noise. Verify that high
voltage power is separated from the low voltage communication
wires.
√ Check for incorrectly wired or loose connections be tween system
components (devices).
√ Check for a high voltage source of noise close to the system.
Automatically clears when
the system detects the is-
sue no longer exists.

18
Table 11. Alert Codes and Troubleshooting
Alert Code Priority
Condition
Applicable System
Component(s)
Alert Text Component or System Operational State
and Troubleshooting Tip How to clear the alert code
114 Moderate /
Critical
Furnace, air handler, EIM or
IHarmony
There is a frequency /
distortion problem with
the power to a specic
system component.
√ This alert code may indicate transformer overload ing.
√ Check the voltage and line power frequency.
√ Check the generator operating frequency, if the system is running
on back-up power.
√ Correct voltage and frequency problems.
√ System will resume normal operation ve seconds after fault
recovered.
√ All applicable system component outputs are dis abled – moderate
condition.
√ After 10 minutes, the priority condition is escalated – critical
condition.
√ Damper control module will operate in central mode only until proper
voltage is restored or frequency distortion is resolved – moderate
condition.
Automatically clears when
the system detects the is-
sue no longer exists.
115 Critical Furnace, air handler or EIM
Primary 24VAC power
to a system component
control is lower than the
required range of 18 to
30VAC.
√ Check and correct voltage.
√ Check for additional power-robbing system compo nents (devices)
connected to system.
√ This alert code may require the installation of an ad ditional or larger
VA transformer.
Automatically clears when
the system detects the is-
sue no longer exists.
120 Moderate
All iComfort series
thermostats, furnace, air
handler, outdoor unit, EIM or
iHarmony
There is a delay in the
system component
responding to the sys-
tem.
Typically this alert code does not cause any operational issues and will
clear on its own.
√ This alert code is usually caused by a delay in the outdoor unit
responding to the thermostat.
√ Check all wiring connections.
Automatically clears after
an unresponsive system
component (device) re-
sponds to any inquiry.
124 Critical
All iComfort series
thermostats, furnace, air
handler, outdoor unit, EIM or
iHarmony
The thermostat has lost
communication with a
system component for
more than three min-
utes.
System component has lost communication with the thermostat.
√ Check the wiring connections.
√ Ohm wires.
√ Cycle power.
√ Check voltage at component.
This alert code stops all associated system operations and waits for
a heartbeat message from the system component that is not commu-
nicating.
Automatically clears after
communication is re- estab-
lished with applicable sys-
tem component (device).
125 Critical
All iComfort series
thermostats, furnace, air
handler, outdoor unit, EIM or
iHarmony
There is a hardware
problem on a system
component control.
There is a control hardware problem.
√ Replace the control if the problem prevents opera tion and is
persistent.
√ Damper control module will remain in non-zone mode (all dampers
open) for ve minutes after priori ty condition no longer exist.
√ Remove jumper if present on indoor unit between Rand W2 if
equipment interface module is in use.
Automatically clears 300
seconds after the issue no
longer exists.

19
Table 11. Alert Codes and Troubleshooting
Alert Code Priority
Condition
Applicable System
Component(s)
Alert Text Component or System Operational State
and Troubleshooting Tip How to clear the alert code
130 Moderate EIM Air handler jumper is
missing.
√ Conguration jumper missing on equipment inter face module.
√ Install the missing jumper.
NOTE: This is applicable in non-communicating applications only).
Automatically clears after
the missing or incorrectly
installed jumper is installed
or corrected.
131 Critical
All iComfort series
thermostats, furnace, air
handler, outdoor unit, EIM or
iHarmony
System component
control parameters are
corrupted.
√ Replace the system component control if heating or cooling is not
available.
√ Try resetting the thermostat
Will automatically clear
when system component
(device) passes memory
self-test or system compo-
nent control is re placed.
132 Critical Air handler, EIM or
iHarmony
System component
control software is cor-
rupted
√ Recycle power.
√ If failure re-occurs, replace the system component control.
Manual system power reset
is re quired to recover from
this alert code.
180 Critical Furnace, air handler or EIM
The thermostat has
found a problem with
a system component’s
outdoor temperature
sensor.
In normal operation after system component control recognizes sen-
sors, the alarm will be sent if valid temperature reading is lost.
√ Compare outdoor sensor resistance to temperature / resistance
charts in unit installation instructions.
√ Replace sensor pack if necessary.
√ At the beginning of (any) conguration, furnace, air- handler control
or equipment interface module will detect the presence of the
sensor(s).
√ If detected (reading in range), appropriate feature will be set as
‘installed’ and shown in the ‘About’ screen.
Automatically clears upon
con guration, or sensing
normal values.
310 Moderate Furnace, air handler, EIM or
iHarmony
There is a discharge
air temperature sensor
issue.
Compare discharge temperature sensor resistance to temperature /
resistance charts in system component installation instruction.
√ Replace discharge air sensor if failed.
√ If applicable, iHarmony will operate in non-zone mode (all dampers
open).
NOTE: Conrm there is no short or open circuits in the iComfort
thermostat connections to any of the other components in
the communication system.
Automatically clears 30
seconds after condition is
detected as recovered or
after system restart.
345 Critical Air handler, EIM or heat
pump
The O relay on the sys-
tem component has
failed. Either the pilot
relay contacts did not
close or the relay coil
did not energize.
Possible O relay / stage 1 failure.
√ Pilot relay contacts did not close or the relay coil did not energize.
√ Replace system component (device) control.
√ If error is applicable to the XC/XP 25, the outdoor control will need
to be replaced.
Automatically clears after
the fault recovered follow-
ing reset.
347 Critical Furnace, air handler or EIM
The Y1 relay on the ap-
plicable system compo-
nent has failed. Either
the pilot relay contacts
did not close or the
relay coil did not ener-
gize.
√ System operation will stop.
√ Possible Y1 relay / stage 1 failure.
√ Pilot relay contacts did not close or the relay coil did not energize.
√ There is no input back to the applicable system component control.
Automatically clears af-
ter reset and Y1 input
sensed.

20
Table 11. Alert Codes and Troubleshooting
Alert Code Priority
Condition
Applicable System
Component(s)
Alert Text Component or System Operational State
and Troubleshooting Tip How to clear the alert code
380 Moderate /
Critical EIM
Interlock relay failure
(IFC or AHC mode on-
ly).
√ Interlock relay is energized, but input is not sensed after three
seconds.
√ There will be no heating or cooling due to this alert code – moderate
condition.
√ De-energize interlock relay and energize after ve minutes if
demand is still present – critical condition.
Automatically clears after
fault recovered.
381 Moderate /
Critical EIM
Interlock relay stuck
(IFC or AHC modes
only)
√ Interlock relay continuously sensed (with relay off).
√ There is no heating and cooling operation – moderate condition.
√ After 10 minutes if event still exist it will be escalated – critical
condition.
Automatically clears 30
seconds after fault clears
382 Moderate EIM
Relay W1 failure
(IFC and AHC modes
only)
W1 relay is energized but input is not sensed after three seconds. Automatically clears when
W1 relay input is sensed.
418 Moderate EIM and outdoor unit There is a faulty W out-
put circuit.
√ W terminal is energized while in cooling mode.
√ Possible cause may be a stuck closed relay on the control, or
something external to the control that is energizing W terminal when
it should not be energized.
√ Disconnect any wiring from the W terminal.
√ If 24VAC is still on the terminal, then it is a stuck relay.
√ If 24VAC disappears, then there is a need to check any of the wires
hooked up to the W terminal.
Automatically clears after
fault signal is re moved.
419 Critical EIM and outdoor unit
The W output has re
ported more than ve
errors
√ The system will shut down the outdoor unit.
√ The W output (code E418) on the outdoor unit has reported more
than ve strikes.
√ Disconnect thermostat wire from W and verify there is no 24VAC on
the W.
√ If 24VAC is present, replace the outdoor control.
Automatically clears after
power recycled.
420 Critical Air handler or EIM
The heat pump defrost
cycle has taken more
than 20 minutes to
complete
√ Defrost cycle lasts longer than 20 minutes.
√ Check heat pump operation.
√ This is applicable only in communicating indoor unit with non-
communicating heat pump.
Automatically clears when
W1 signal is re moved.
421 Critical EIM and outdoor unit
The W output terminal
on the outdoor unit is
not wired correctly.
Voltage sensed on W output terminal when Y1 out is deactivated.
Automatically clears once
volt age is not sense on out-
put for power cycled.
594 Moderate /
Critical EIM
Pre-coil discharge air
temperature sensor
problem (DFM mode
only). Advances from
moderate to critical af-
ter ten (10) minutes.
√ Interlock relay energized, but input not sensed after three seconds.
√ No heating and cooling operations.
√ De-energize interlock relay and re-energized ve minutes later if
demand is still present.
Alarm clears ve minutes
after fault clears.