Goodman GM9S80 Service And Troubleshooting page 8

SYSTEM OPERATION
W R G C Y
24 Volt Humidifier Connection
Furnace Startup
1. Close the manual gas shutoff valve external to the
furnace.
2. Turn off the electrical power to the furnace.
3. Set the room thermostat to the lowest possible setting.
4. Remove the burner compartment door.
NOTE: This furnace is equipped with an ignition device
which automatically lights the burner. Do not try to light the
burner by hand.
5. Move the furnace gas valve manual control to the OFF
position.
6. Wait five minutes then smell for gas. Be sure check
near the floor as some types of gas are heavier than
air.
7. If you smell gas after five minutes, immediately follow
the safety instructions in the Safety Considerations on
page 2 of this manual. If you do not smell gas after five
minutes, move the furnace gas valve manual control
to the ON position.
8. Replace the burner compartment door.
9. Open the manual gas shutoff valve external to the
furnace.
10. Turn on the electrical power to the furnace.
11. Adjust the thermostat to a setting above room
temperature.
12. After the burners are lit, set the thermostat to desired
temperature.
Gas Heat Sequence of Operation
Call for Heat
• On a call for heat, the thermostat contacts close & the
control board receives 24 VAC on the W terminal.
• The control board microcomputer runs its self-check
routine.
• The control verifies the limit switch is closed (24 VAC
on Pin 8 of the 12 Pin connector).
8
24V HUM Terminal is
energized when pressure
switch is closed
24 VOLT HUM. &
HUMIDISTAT
• The control verifies 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 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 flame is sensed.
• After 30 seconds the indoor blower is energized on
heating speed.
• When the thermostat is satisfied:
• The gas valve is de-energized.
• The inducer remains energized for the post purge
period (15 seconds).
• The indoor blower runs for the selected off delay period
(90 seconds by default, adjustable from 30 – 180
seconds).
Heating Mode Speed Selection
To change the main blower speed in HEATING mode, follow
the following steps:
1. Press left or right button till LED displays "gA1 "(for
single stage HEATING). Press center button and LED
will display the selected speed number as Fxx (xx:
Blower speed number).
2. The control shall rotate available speed number ev-
ery time Left/Right switches are pressed. Table be-
low shows the available speeds for Low & High heat
mode.
3. When the center switch is pressed, the current dis-
played speed shall be selected, and control shall
apply the newly selected speed in next heating call.
NOTE: Always refer to the Heating Chart to choose
from available heating speeds
THERMOSTAT CALL
W/W1
Heating Speed Table for 1 Stage IFC
Continuous Fan Mode Speed Selection
To change the main blower speed in circulation mode, follow
the following steps:
1. Press the left or right switch until LED displays "FSd".
Press the center switch and LED will display the select-
ed speed number as Fxx (xx: Blower speed number
from 1 to 9). F01 is the default speed for circulation.
2. The control will rotate available speed number every
time left/right switches are pressed. All 9 speeds are
available for circulation.
AVAILABLE SPEEDS
F01
F02 (DEFAULT)
F03
F04