User Guide

Step 3: System Operation
1. Perform necessary safety checks. Consider flame
safety, limit switch, and vent system.
2. Operate unit through a complete call for heat cycle.
LIA231-1
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Bottom Right Corner of Control Board
d. If clear, remove the bottom mounting bracket from
the control board and re-attach the bracket to the
control box.
e. Install the control board into the control box by
sliding the mounting tab on the control board
through the slots in the top of the control box.
f. Attach the control board to the bottom mounting
rail of the furnace control box.
g. Continue on to Step-5 of the installation process.
5. Connect all line voltage, low voltage, and accessory
wires.
6. Connect wiring harness edge connector to circuit
board.
7. Set blower off delay. Blower off delay DIP switch SW1
is found near the right-hand corner of the board (see
Figure 1).
8. Re-install control box cover.
Note: Do not connect thermostat wires to control board
until system tests are complete.
System Tests
Step 1: Component Self Test
1. Begin component test sequence by ensuring that
thermostat is turned to OFF position and thermostat
wires are disconnected. Turn power ON and engage
blower door switch. With a short piece of wire, briefly
short TEST/TWIN terminal to Com/24V terminal. The
component test sequence follows:
A. Status LED will flash code and will then turn ON the
inducer motor.
B. Inducer motor will run for the entire component
test.
C. Hot surface ignitor and blower motor heat speed
will run for 10 secs.
D. Blower motor cool speed will turn ON for 10 secs.
2. Repair, replace, or service any failing components from
the component self test. The gas valve is not energized
during the self test.
3. Turn power OFF.
4. Disengage the blower door switch.
5. Connect thermostat wires.
6. Install blower door and access door.
7. Turn power ON.
8. Turn gas ON.
Upflow Condensing Furnaces:
With the blower door(s) removed, locate the LED on the
control board. Check the sides of the casing. You may be
able to utilize the unused condensate drain opening or
electrical knock-out as an observation port on some models.
A 1/2-inch electrical box knock-out plug must be installed
when this option is used.
All Furnaces:
1. Measure the height of the floor for upflow furnaces or
off the blower shelf on downflow/horizontal furnaces.
2. Measure the distance from the front inside edge of the
casing.
3. Orient the blower door to the correct position and mark
this location on the front of the blower door.
4. Using a step-drill or chassis punch, drill a 1 1/2-inch hole
in the blower door.
5. Install a sight glass in the blower door (Use Carrier Part
No. 323017-201 or 323018-201, or equivalent).
6. A 1/2 inch hole may be drilled and an electrical box plug
may be used and are available from hardware stores or
electrical suppliers.
Note: DO NOT INSTALL AN OBSERVATION PORT OR
SIGHT GLASS THROUGH WARNING LABELS ON
FURNACE.
CAUTION!
A loose fitting sight glass should be sealed with clear
silicone to prevent leakage and sight glass from falling out.
7. Install Fault Code Label in a convenient location on the
blower door adjacent to the sight glass.
Step 2: Flame Sensor Operation
Connect a DC microammeter in series with flame sensor.
Initiate a heat call. After burners ignite and stabilize,
measure flame current. Nominal flame current is between
4.0 and 6.0 microamps DC. If flame current reading is less
than 4.0 microamps DC, either replace or remove and
clean flame sensor with a fine grade steel wool. When
the flame current falls to 0.5 microamps DC, the furnace
control will lock out.
CAUTION!
Do not install a sight glass or observation port between
the furnace and the blower compartment. To avoid having
carbon monoxide drawn into the living area, do not cover
any port with tape, and do not leave the unit unattended
and operational with the blower door off. Failure to follow
this warning could result in possible damage to this
equipment, serious illness or personal injury, or death.
Note: If a sight glass is not installed, current fault code
will be erased when blower door is removed.
The ICM281 furnace control has LED fault code capability. To
utilize this feature, it is necessary to field install a sight glass
or observation port. The location of this device will vary
depending on the model of the furnace.
Optional Observation
Port/Sight Glass Installation
Twinning Instructions
A 3/16” quick connect terminal is provided on the ICM281
control board for communication between another ICM281
control board for furnace twinning.
To configure your control boards for twinning, simply (1) install
each control board according to the installation instructions;
(2) connect the TWIN terminals together (see Fig. 1); and (3)
connect the 24 VAC common together. A common ground
between the two furnaces is also required.
If the 24 VAC supplies to the control are in phase, both
furnaces will turn the blower on and off synchronously and at
the same speed. If the 24 VAC supplies are not in phase, then
neither control will respond to the thermostat commands and
the status LED will flash rapidly.
Figure
1