Installation, Operation & Application Guide
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ICM2914
Gas Ignition Replacement Board
• Controls blower motors, gas valve, & spark ignitor in sequence
• Protects against short cycling
• Selectable Heat/Cool blower off-delay time
• Flash codes from the onboard LED indicate specific problems for easier troubleshooting
• Repeated ignition failures or flame losses will disable heat operation for safety
FEATURES
The ICM 2914 is a form, fit, and functional replacements for the boards shown in the cross-reference
section of this guide. The control boards are designed as automated gas ignition controls which monitor
the ignition sequence including the inducer, pressure switch, spark ignition, gas valve, flame sense, and
circulating blower while maintaining full safety circuit monitoring including the high limit switch, roll out
switch and auxiliary limit switch circuits. Onboard diagnostics will indicate when a fault condition exists.
INTRODUCTION
• Line voltage: 460 VAC
• Line frequency: 50/60 Hz
• Control voltage: 18-30 VAC
• Circulating blower: 4FLA @ 277 VAC
• Hi-efficiency blower: 10 mA @ 24 VAC
• Inducer blower: 10 mA @ 24 VAC
• Combined gas valve load: 1.5 A @ 24 VAC
• Minimum flame signal threshold: 0.75 uA
SPECIFICATIONS
TRANE P/N #: D674712P01
REPLACES
CAUTION! To service control, and prior to disconnection, label all wires. Failure to do so may
result in wiring errors that can cause dangerous operation.
1. Turn thermostat to the OFF position or set it to the lowest possible setting.
2. Turn OFF the electrical supply to furnace.
3. Turn OFF the gas supply to furnace.
CAUTION! Failure to turn off gas and electric supplies can result in explosion, fire, death or
personal injury.
4. Remove the furnace blower and control access doors.
5. Disconnect the thermostat wires and humidifier wires (if equipped with a humidifier).
6. Disconnect the line voltage, blower, electronic air cleaner wires (if equipped) and transformer wires.
7. Remove screws and any other fasteners and the old circuit board.
8. Examine the control and the control box for water stains.
9. Make repairs if any sources of water leakage are found. Be sure to check humidifiers, evaporator
coils and vent systems in the area of the control.
REMOVE EXISTING CONTROL
1. Ground yourself. When handling the circuit board; hold it by the edges.
2. Fasten the circuit board with the retaining screws.
3. Connect all line voltage, low voltage and accessory wires.
4. Verify the sequence of operation.
INSTALL NEW CONTROL
The control will go into a 1-hour soft lockout if the following faults are detected:
• Limit switch open 4 times in one heat call
• Ignition failed (flame not sensed) 4 times in one heat call
• Flame lost after successful ignition 3 times in one heat call
• Gas valve sensed on when it should not be
• Gas valve sensed off when it should be on, 10 times in one heat call
Flame sensed while the gas valve is closed puts the control in lockout state, but lockout clears after the
blower off delay is complete (90 seconds or 60 seconds, depending on jumper selection).
LOCKOUT
Function
Time
Units
Heat “ON” delay
45
Sec
Cool “ON” delay
2
Sec
Flame recognition time
0.8
Sec
Flame establishing period
7
Sec
Flame failure response time (before 10
seconds after trial for ignition period)
2
Sec
Flame failure response time (otherwise) 0.8
Sec
Recycle time
27
Sec
Lockout time
300
Sec
Pre–purge time
20
Sec
Post–purge time
5
Sec
Auto-restart purge time
5
Sec
Trial for ignition period
7
Sec
Interpurge time
60
Sec
Auto restart time
60.
Min
Retry
2
Each
Recycle
10
Each
Heat fan OFF delay
60 or 90 sec., field selectable, default will be 90 sec.
Cool fan OFF delay
0 or 45 sec., field selectable, 45 sec. will be default for
HEM, 45 sec. will be default for PSC.
(@ 25 VAC, 60 Hz, 25ºC unless noted)
TIMING
Fault code retrieval & clearing
When powering on, the control
flashes the last four error codes that
have occurred in the last 14 days.
The control will flash the newest error
first and oldest error last. The fault
memory can be manually erased by
powering on with a G call in place
and toggling W 3 times.
Two LED’s on the board
• Status LED (Green)
– Slow Flash: Normal operation
with no call for heat
– Fast Flash: Normal operation with
call for heat
• Fault LED (Red)
– See table
FAULT CODE TABLE
# of Flashes
Error
2
External lockout (retries or recycles
exceeded)
3
Pressure switch/Inducer error
4
Open limit switch and rollout
5
Flame sensed when no flame should
be present
6
Not used
7
External gas valve circuit error
8
Low flame sense
Solid Red
Internal board error
Solid Red w/solid
‘STATUS’ LED
Continuous reset caused by an internal
board error
On a call for heat (24 VAC on the W input), the following occurs:
• Upon a call for heat the control checks the status of the pressure switch; if the pressure switch is open,
the control will energize the draft inducer.
• When the control verifies the pressure switch has closed, the control will start a 20-second prepurge.
• When the pre-purge time delay is over, the control will energize the gas valve and initiate spark.
• The ignitor must be de-energized when the flame is sensed or at the conclusion of the trial for ignition
period, whichever comes first.
• When flame is sensed, the control will energize the circulator fan within the ON-delay period.
When the call for heat is terminated, the following occurs:
• The control shall de-energize the gas valve and the draft inducer within the post purge period.
• When the heat mode fan OFF delay timer expires, the control will de-energize the circulator fan.
With a call for cooling, the following occurs:
On a call for cooling (24Vac on Y and G), the circulator fan is energized within the cool on delay period.
The control will ignore a call for Y without a call for G. After the thermostat is satisfied, the compressor
is de-energized and the jumper selected cool Off delay period begins. Following the cooling Off delay
period, the circulator fan is de-energized.
OPERATION
Use caution when installing and servicing the furnace to avoid and control electrostatic
discharge; ESD can impact electronic components. These precautions must be followed to
prevent electrostatic discharge from hand tools and personnel. Following the precautions will
protect the control from ESD by discharging static electricity buildup to ground.
1. Disconnect all power to the furnace. Do not touch the control or the wiring prior to discharging your
body’s electrostatic charge to ground.
2. To ground yourself, touch your hand and tools to a clean, metal (unpainted) furnace surface near
the control board.
3. Service the furnace after touching the chassis. Your body will recharge with static electricity as you
shuffle your feet or move around, and you must reground yourself.
4. Reground yourself if you touch ungrounded items.
5. Before handling a new control, reground yourself, this will protect the control. Store the used and
new controls in separate; containers before touching ungrounded objects.
6. ESD damage can also be prevented by using an ESD service kit.
ELECTROSTATIC DISCHARGE (ESD) PRECAUTIONS
ELECTRICAL SHOCK HAZARD! Before installing this unit, turn off power at the
main service panel by removing the fuse or switching the appropriate circuit breaker to
the OFF position. Follow all Local, State and National Electrical Codes when installing
this device.
CAUTION! Only trained personnel should install or service heating equipment. When
working with heating equipment, be sure to read and understand all precautions in the
documentation, on labels, and on tags that accompany the equipment. Failure to follow
all safety guidelines may result in damage to equipment, severe personal injury or death.
> > > CAUTION < < <
Automatic Restart Purge
Lockout resets automatically after 1 hour. Whether a call is in place or not, the control activates the
inducer blower for 5 seconds. The inducer will deactivate and ensure the pressure switch is not stuck
closed before starting a new heat call.
Automatic Inducer Pre-purge Reset
If the pressure switch remains open after 2 minutes of draft inducer run time, the draft inducer will be de-
energized for 30 seconds. The sequence will start again checking for an open pressure switch.
Continuous Fan Off delay (single stage units only)
On a call for continuous fan (24 VAC on G), the circulator fan is energized. During a call for cooling
while the cool “On” delay is in place, the control will not respond to the fan input (G). If the fan was
called prior to the call for cool, the circulator fan will remain energized during the Cool “On” delay. When
the call for continuous fan is terminated, the selected cool Off delay period begins. When the cool Off
delay period expires, the circulator fan is de-energized.
Note:
If the fan is called prior to a call for heat,
the circulator fan will remain energized during the entire call for heat sequence.
Fault Code Retrieval
When powering on, the control flashes the last four error codes that have occurred in the last 14 days.
The control will flash the newest error first and oldest error last. The fault memory can be manually
erased by powering on with a G call in place and toggling W three times.
Flame Sense Test Points
The ignition board is equipped with a set of flame sense test points. A multimeter can be used to test
flame sense by placing the meters probes on the two test pins and taking a DC voltage reading while
the flame sensor is in the presence of flame. 1VDC = 1µA flame current. Weak or poor flame sense is
represented by a reading of 0.7 VDC or lower.
SPECIAL FEATURES
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