LIAF316
Thermostat interference
There are some thermostats which can interfere with the way the ICM furnace boards sense the call for heat. If you are having any issues with establishing
flame, the first step would be to remove all the thermostat wires from the board and temporarily jump R – W to test. If the furnace cycle completes, remove
the jumper, and replace the existing thermostat with a battery-operated thermostat or a hardwired thermostat which uses a R & C connection.
Weak or intermittent spark
Make sure the furnace frame is grounded to earth ground. Ensure the common of the 24 VAC is grounded to Earth ground. Check or replace the spark
igniter. Check the primary and secondary voltage of the transformer for proper voltage.
Flame Loss
• Check for bad or dirty flame sensor
• Check thermostat (bypass for testing)
• Check for proper flame sense signal at flame sense test pins
• Check for proper earth ground on furnace.
• 4 flame losses in a single heat call will put the control into a one-hour lockout.
No flame/Ignition failure
If the flame is not established and proven during the initial sequence, there will be two more successive attempts allowed each having a sixty second
inducer purge between attempts. After three successive attempts if the flame is still not proven, there will be a 1 hour lock out before the system will try for
ignition again.
• Check the thermostat (bypass for testing)
• Check the pressure switch
• Check gas valve operation
• Check for good spark & check for good earth ground
Flame out of sequence
Flame out of sequence represents a scenario where flame is sensed while the gas valve is closed. The control goes into a lockout state when flame is out
of sequence and the indicator LED blinks the appropriate code (see “lockout” section).
• Check and replace flame sensor
Furnace does not ignite and main blower runs
continuously
Check the high temperature limit switch for open circuit. Check all safeties. Clean or replace air filter. Check duct work and return air ducts for blockages.
TROUBLESHOOTING
B
24 VAC common
C
24 VAC common
ECM
Electonically commutated motor
F1
Fuse
FS
Flame sensor
GND
Ground
GV
Gas valve
IDM
Induced draft motor
K1, K2 Gas valve relays
LIM
Limit switch
PRI
Transformer primary
PS
Pressure switch
R
24 VAC
ROS
Roll out switch
SEC
Transformer secondary
TH
Transformer 24 VAC hot
TR
Transformer 24 VAC common
1. N/A
2. Gas valve
3. Pressure switch in
4. Flame sensor
5. N/A
6. Fusible link (Roll out switch)
7. Common (24 VAC), B
8. Limit switch (out)
9. Limit switch (in)
LEGEND
9-PIN CONNECTION
B
24 VAC common
C
24 VAC common
ECM
F1
Fuse
FS
Flame sensor
GND
Ground
GV
Gas valve
IDM
Induced draft motor
N/A
K1, K2 Gas valve relays
LIM
Limit switch
PRI
Transformer primary
PS
Pressure switch
R
24 VAC
ROS
Roll out switch
SEC
Transformer secondary
TH
Transformer 24 VAC hot
TR
Transformer 24 VAC common
1. N/A
2. Gas valve
3. Pressure switch in
4. Flame sensor
5. N/A
6. Fusible link (Roll out switch)
7. Common (24 VAC), B
8. Limit switch (out)
9. Limit switch (in)
LEGEND
9-PIN CONNECTION
B
24 VAC common
C
24 VAC common
ECM
Electonically commutated motor
F1
Fuse
FS
Flame sensor
GND
Ground
GV
Gas valve
IDM
Induced draft motor
K1, K2 Gas valve relays
LIM
Limit switch
PRI
Transformer primary
PS
Pressure switch
R
24 VAC
ROS
Roll out switch
SEC
Transformer secondary
TH
Transformer 24 VAC hot
TR
Transformer 24 VAC common
1. N/A
2. Gas valve
3. Pressure switch in
4. Flame sensor
5. N/A
6. Fusible link (Roll out switch)
7. Common (24 VAC), B
8. Limit switch (out)
9. Limit switch (in)
LEGEND
9-PIN CONNECTION
B
24 VAC common
C
24 VAC common
ECM
Electonically commuted motor
F1
Fuse
FS
Flame sensor
GND
Ground
GV
Gas valve
IDM
Induced draft motor
K1, K2, K3 Gas valve relays
LIM
Limit switch
PRI
Transformer primary
PS
Pressure switch
R
24 VAC
ROS
Roll out switch
SEC
Transformer secondary
TH
Transformer 24 VAC hot
TR
Transformer 24 VAC common
1. Stage two of gas valve (HI)
2. Stage one of gas valve (LO)
3. Pressure switch in
4. Flame sensor
5. N/A
6. Fusible link (Roll out switch)
7. Common (24 VAC), B
8. Limit switch (out)
9. Limit switch (in)
LEGEND
9-PIN CONNECTION
Blower
ICM2914
MADE IN THE USA
LED2
FAULT
LED1
STATUS
HEAT
COOL
90 60
0
45
BLOWER RELAY
Inducer
PARK
B
G
W
Y
R
E_GND
G
W
Y
R
C
Thermostat
PRI
460 VAC
SEC
24 VAC
Earth
Ground
ECM
ECM
L1
L2
K4
K3
24 VAC
Load
Load
IN
IN
Spark
Electrode
Earth Ground
Earth Ground
WIRING DIAGRAM
FLAME CURRENT
1VDC = 1uA
TR
TH
F1
Blower
BLOWER
ICM2913
MADE IN THE USA
LED2
FAULT
LED1
STATUS
HEAT
COOL
90 60
0
45
BLOWER RELAY
Inducer
PARK
B
C
Load
Load
IN
IN
Earth Ground
B
G
W
Y
R
E_GND
G
W
Y
R
C
Thermostat
IDM
PRI
230 VAC
SEC
24 VAC
Earth
Ground
L1
L2
Spark
Electrode
Earth Ground
WIRING DIAGRAM
FLAME CURRENT
1VDC = 1uA
TR
TH
F1
Earth
Ground
Blower
ICM2916
MADE IN THE USA
LED2
FAULT
LED1
STATUS
HEAT
COOL
90 60
0
45
BLOWER RELAY
Inducer
PARK
B
G
W
Y
R
E_GND
G
W
Y
R
C
Thermostat
PRI
230 VAC
SEC
24 VAC
TR
TH
ECM
L1
L2
K4
K3
24 VAC
Line
VAC
IDM
Earth Ground
Spark
Electrode
Earth Ground
WIRING DIAGRAM
FLAME CURRENT
1VDC = 1uA
F1
WIRING DIAGRAM
ICM2915
LED1
STATUS
Thermostat
Earth
Ground
Spark
Electrode
F1
G
W2
W1
R
C
Y
W1
R
B
W2
G
Y
HEAT
COOL
90
60
0 45
L2_BLO
HIGH
LOW
L2_IND
IND_HI
IND_LO
NC
NO
COM
NC
NO
COM
NC
NO
COM
NC
NO
NC
NO
COM
NC
NO
COM
NC
NO
COM
SEC
24 VAC
PRI
230 VAC
C
R
L2
L1
ECM Controller
R
B
IDM
Earth
Ground
PS
ROS
LIM
GV
PS
RO
FS
K2 K1
(C)
(R)
PRI
460 VAC
SEC
24 VAC
Earth
Ground
Earth
Ground
B
G
W
Y
R
E_GND
G
W
Y
R
C
Thermostat
TR
TH
Chassis
Ground
Flame
Sensor
CONNECTION DIAGRAM
LIM (OUT)
LIM (IN)
PS
ROS
LIM
Flame
Sensor
GV
PS
RO
LIM (OUT)
FS
K2 K1
(C)
(R)
PRI
230 VAC
SEC
24 VAC
Earth
Ground
Earth
Ground
B
G
W
Y
R
E_GND
G
W
Y
R
C
Thermostat
TR
TH
Chassis
Ground
CONNECTION DIAGRAM
LIM (IN)
PS
ROS
LIM
GV
PS
RO
FS
K2 K1
(C)
(R)
PRI
230 VAC
SEC
24 VAC
Earth
Ground
Earth
Ground
B
G
W
Y
R
E_GND
G
W
Y
R
C
Thermostat
TR
TH
Chassis
Ground
Flame
Sensor
CONNECTION DIAGRAM
LIM (OUT)
LIM (IN)
CONNECTION DIAGRAM
(C)
(R)
PRI
230 VAC
SEC
24 VAC
Earth
Ground
TR
TH
Chassis
Ground
B
G
W1
W2
R
Y
G
W2
W
R
C
Thermostat
Y
PS
ROS
LIM
GV
PS (IN)
HI
LO
ROS
FS
K3
K1
Flame
Sensor
LIM (OUT)
LIM (IN)
K2
B (COM)
LIAF316.indd 2
LIAF316.indd 2
4/14/22 11:14 AM
4/14/22 11:14 AM
