ICM Controls ICM2818 Installation, Operation & Application Manual page 2

REMOVING EXISTING CONTROL
CAUTION! Failure to turn off gas and electric supplies can result
in explosion, fire, death, or personal injury.
1. Turn thermostat to OFF position or set to lowest possible setting.
2. Turn OFF electrical supply to furnace.
3. Turn OFF gas supply to furnace.
4. Remove furnace blower and control access doors.
5. Remove control box cover.
6. Disconnect thermostat wires and humidifier wires (if applicable).
7. Disconnect line voltage, blower, electronic air cleaner wires
(if applicable), and transformer wires.
8. Remove wiring harness from circuit board.
9. Remove screws or any other fasteners.
10. Examine control and control box to check for water stains.
11. Make repairs if any sources of water leakage are found.
Be sure to check humidifiers, evaporator coils, and vent systems
around the control.
TIMING SPECIFICATION
DELAY
Heat Operation
Inducer blower on delay
Gas valve delay on make
HSI delay on make
Heat blower on delay
Heat blower off delay
Inducer blower off delay
Ignition Trial
Inter-Purge (Retrial)
Ignition Activation Period
Flame Establishing Period
Flame Failure Response Time
Fan Operation
Cool blower on
Cool Blower off
Auto reset lockout
2
INSTALLING NEW CONTROL
1. GROUND YOURSELF. When handling the circuit board, hold it by the
2. Mount and fasten the circuit board using the corner retaining screws.
3. Connect all line voltage, low voltage, and accessory wires.
4. Verify the sequence of operation.
LOCKOUT FEATURES
If the pressure switch is observed to be stuck closed during the
Hardware Safety Check, the red Status LED will blink a 3-flash code and
the inducer blower will remain off until the pressure switch opens.
If the limit switch opens during a heat call, the heat sequence will be
terminated. The red Status LED will indicate a 1-flash code and the
inducer blower and heat blower will turn on if not on already, remaining
energized until the limit switch closes, and the fault case removed. If
this occurs, the status LED will return to display normal operation, the
inducer will turn off within 1 second, the heat blower after 120 seconds,
and the heat sequence will restart.
If the gas valve is sensed open during a fan call, a heat call, or in off
mode, the inducer will be de-energized after 10 seconds, and the
control will enter a 1-hour lockout.
DURATION (SEC)
1
FLAME SENSE TROUBLESHOOTING
30
Flame Not Established
45
1. If the flame is not detected during the 3-second ignition activation
25
120
30
5
45
2. Following the above, the control will enter a 1-hour lockout. This
3
2
Flame Out
0.8 (max)
1. If flame is detected then lost during heat mode, the gas valve will be
1
40
60 minutes
2. If flame loss is recorded five times in a single heat call, the inducer
Flame Out Of Sequence
1. If flame is sensed when not called for, the inducer and heat blower
edges.
period, the ignitor will de-energize within the next 2 seconds. After
45 seconds, the control will retry the activation. After five consecutive
failed ignition attempts, the inducer will be de-energized within 30
seconds.
lockout can be removed prematurely by removing the heat call for 2
seconds or removing power between R and C for 2 seconds.
de-energized within 1 second. The heat blower and inducer motors
will remain on while the heat sequence is restarted after a 45 seconds
delay.
will be de-energized within 30 seconds, the heat blower after 120
seconds, and the control will lockout for 1 hour. The red status LED
will show a 4-flash code.
motors will be energized until the fault condition is removed. The
control will enter a 1-hour lockout, and the yellow status LED will flash
rapidly.