GC9C96 Service Manual

SYSTEM OPERATION
14
inside the furnace junction box.
The integrated control module humidier terminal (HUM H) is
energized with 115 volts whenever the induced draft blower
is energized. The integrated control module electronic air
cleaner terminal (EAC H) is energized with 115 volts whenever
the circulator blower is energized. This terminal can also be
used to provide 115 volt power to a humidier transformer.
The remaining primary transformer wire would be connected
to the Line N on the control board.
W2 W/W1 R G C Y/Y1 Y2
115 VAC EAC
115 VAC HUM



The furnace integrated control module is equipped with
a low voltage terminal for providing power to an optional
eld-supplied 24 volt humidier. The 24V HUM terminal
is energized any time the draft inducer is powered. See
connection diagram below.
 This is a 24 volt circuit only, the common connection
must be on C terminal of the low voltage terminal strip (where
thermostat wires are connected). Wiring for this circuit must
NOT be connected to the line N location where line voltage
neutral wires are connected.
W2 W/W1 R G C Y/Y1 Y2
24V HUM
Terminal is
energized when
pressure switch
is closed
24 VOLT HUM.
& HUMIDISTAT




• On a call for heat, the thermostat contacts close & the
control board receives 24 VAC on the W1 terminal.
• The control board microcomputer runs its self-check
routine.
• The control veries the limit switch is closed (24 VAC on
Pin 8 of the 12 Pin connector).
• The control veries that pressure switch circuit is open
(0 VAC on Pin 5).
• The control module performs a gas valve circuitry check
to verify gas valve relay state and presence of voltage
at the valve.
• The system will energize the Induced draft blower.
• The pre-purge period begins once the low re pressure
switch is detected closed (24 VAC on Pin 5).
• After the completion of pre-purge, the control will
energize the igniter.
• After completion of the ignitor warm-up period:
• The gas valve is energized.
• The ignitor is de-energized as soon as ame is sensed.
• After 30 seconds the indoor blower is energized on
heating speed.
• When using a single-stage heating thermostat, the
furnace will transition to 2nd stage gas heat by either a
xed time or auto mode depending on menu selections
made by the installer.
• The inducer motor is enabled at high speed.
• Closure of the 2nd stage pressure switch will energize
the high re stage of the gas valve.