Sequence Of Operation - ICM Controls ICM2812ж ICM2812-KIT Installation, Operation & Application Manual

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 OFF position or set it to the lowest possible setting.
2. Turn OFF electrical supply to furnace.
3. Turn OFF gas supply to furnace.
CAUTION: Failure to turn off gas and electric supplies can result in explosion, fire, death, or personal injury.
4. Remove furnace blower and control access doors.
5. Disconnect thermostat wires and humidifier wires (if equipped with a humidifier).
6. Disconnect 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 control and control box to check 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.
1. Ground yourself. When handling circuit board, hold it by the edges.
2. Fasten circuit board with retaining screws.
3. Connect all line voltage, low voltage, and accessory wires.
4. Verify the sequence of operation.
On the application of power, the ICM2812 will continuously monitor the rollout switch, limit switch, pressure switch, gas valve output
and flame sense.
During a Call for Heat, the control makes sure the limit switch is closed and the pressure switch contact is open before turning on the
Inducer blower, which will be energized for the 30-second pre-purge. Following the pre-purge period, the pressure switch contact is
closed and power is applied to the hot surface ignitor (there is a 19-second warm-up period), both gas valves are energized. Once
flame is established and sensed the ignitor is turned off.
1STG (Single Stage): After the 30 seconds heat blower on delay the high (HI HEAT-H) speed is energized.
2STG (Dual Stage): After 5 seconds the high gas valve (MV HI) is turned off. The low (LO HEAT-H) speed blower will energize
after the 30 seconds heat blower on delay. The ICM2812 will switch to second stage heat after 5 minutes of
continuous operation; the high gas valve (MV HI) is re-energized along with the low gas valve (MV LO) and the
main blower will switch to the high (HI HEAT-H) speed for the duration of the heat call.
Once the heat call is satisfied; the blower is switched to the low (LO HEAT-H) speed; the Inducer Draft motor turns off after the 25
second post purge delay and the blower motor turns off after the preselected heat blower off delay of either 100 or 150 seconds.
Fan: A fan call from the thermostat will energize the blower motor without delay at low (LO HEAT-H) speed. The blower is turned off
without delay when the Fan call is removed.
Cooling: A cooling call from the thermostat will energize the blower motor at high (COOL-H) speed after the 6 second cool blower
on delay. The blower is turned off 45 seconds after the cooling call is satisfied.
Flame not established
1. If flame is not established during the 4 second initial sequence then the control will start the next trial for ignition in 60 seconds.
2. There will be 2 more attempts to ignite after the 60 seconds delay, before the respective fault code is triggered and the ignition
trials are stopped.
3. If flame has not been established after the 3 trials for ignition; the control will enter a 60 minute soft lockout and flash the
respective fault code. The lockout can be cleared by cycling the W call or the input power.
4. The blower motor is off until 30 seconds after flame is established and sensed.
Flame out
1. Flame out is considered when flame is lost during heating.
2. When a W signal is present and flame is not sensed, then gas valve will disengage until the next trial for ignition.
3. If flame is not established on the immediate sequence (2 above) then the control will continue with 2 additional trials for ignition.
4. The Inducer and Blower motors will continue running during the flame out scenario.
Flame out of sequence
1. Flame out of sequence represents a scenario when flame is sensed while the gas valve is de-energized.
2. The Inducer and Blower motors will be engaged (if not already running) and continue running for as long as the fault condition
is present.
Remove Existing Control
Install New Control

Sequence of Operation

Flame Sense Troubleshooting Tips