Goodman ACS series Service Instructions Manual page 75

PRODUCT DESIGN
NORMAL SEQUENCE OF OPERATION
Goodman Two-Stage 80% or 90% Furnaces
White-Rodgers 50V51 Integrated Ignition Control
P U
OWER P
The normal power up sequence is as follows:
1. 115 VAC power applied to furnace.
2. Integrated control module performs internal checks.
3. Integrated control module LED will light.
4. Integrated control module monitors safety circuits
continuously.
5. Furnace awaits call from thermostat.
H M
EATING ODE
The normal operational sequence in heating mode is as fol-
lows:
1. R and W1 (or R and W1/W2) thermostat contacts close,
initiating a call for heat.
2. Integrated control module performs safety circuit checks.
3. Induced draft blower is energized on high speed for a 15-
second prepurge. Humidifier terminals are energized with
induced draft blower.
4. Induced draft blower steps to low speed following
prepurge. Low stage pressure switch contacts are closed.
5. Igniter warm up begins upon step to low speed and pres-
ence of closed low stage pressure switch contacts.
6. Gas valve opens at end of igniter warm up period, deliv-
ering gas to burners and establishing flame.
7. Integrated control module monitors flame presence. Gas
valve will remain open only if flame is detected.
8. If the thermostat call is for low heat, gas valve and in-
duced draft blower will continue on low stage. If the call
is for high heat, the gas valve and induced draft blower
will change to high stage.
9. Circulator blower is energized on heat speed following a
fixed thirty (30) second blower on delay. The circulator
blower requires thirty (30) seconds to ramp up to full
speed. Electronic air cleaner terminals are energized with
circulator blower.
10. Furnace is now operating on the specified stage called
for by the two-stage thermostat.
11. Furnace runs, integrated control module monitors safety
circuits continuously.
12. If the two-stage thermostat changes the call from low
heat to high heat, the integrated control module will im-
mediately switch the induced draft blower, gas valve, and
circulator blower to their high stage settings.
13. If the two-stage thermostat changes the call from high
heat to low heat, the control will immediately switch the
induced draft blower and gas valve to their low stage
settings. The circulator blower will remain on high heat-
ing speed for thirty (30) seconds before switching to the
low heat circulating speed.
14. R and W1 (or R and W1/W2) thermostat contacts open,
allowing the gas valve to cycle off.
15. Induced draft blower is de-energized following a fifteen
(15) second post purge. Humidifier terminals are de-
energized.
16. Circulator blower continues running for the selected
heat off delay period (90, 120, 150 or 180 seconds).
The speed run during this period depends on the last
heat call provided by the thermostat.
If the last call for heat was a call for low heat, the air
circulator motor will run on low heat speed for the du-
ration of the heat off delay period (90, 120, 150 or 180
seconds).
If the last call for heat was a call for high heat, the air
circulating motor will run on the high heating speed
for thirty (30) seconds and then switch to the low
heating speed for the balance of the heat off delay
period (60, 90, 120 or 150 seconds).
17. Circulator blower and electronic air cleaner terminals
are de-energized.
18. Circulator blower ramps down to OFF during the 30
seconds following the heat off delay period.
19. Furnace awaits next call from thermostat.
C M
OOLING ODE
The normal operational sequence in cooling mode is as
follows:
1. R and YLO/G or Y/G thermostat contacts close, initi-
ating a call for cool.
2. Integrated control module performs safety circuit
checks.
3. Outdoor fan and compressor are energized to their
appropriate speed.
4. Circulator blower is energized on the appropriate cool
speed at the level and time determined by the se-
lected ramping profile. Electronic air cleaner termi-
nals are energized with circulator blower.
5. Furnace circulator blower and outdoor cooling unit run
their appropriate speed, integrated control module
monitors safety circuits continuously.
6. R and YLO/G or Y/G thermostat contacts open, com-
pleting the call for cool.
7. Outdoor fan and compressor are de-energized.
8. Circulator blower continues running during a cool off
delay period. The OFF delay time and airflow level
are determined by the selected ramping profile.
9. Electronic air cleaner terminals and circulator blower
are de-energized.
10. Furnace awaits next call from thermostat.
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