Service Guide
SYSTEM OPERATION
6
1. 115 VAC power applied to furnace.
2. Integrated ignition control module performs internal
checks.
3. Integrated ignition control module LED will light.
4. Integrated ignition control monitors safety circuits contin-
uously.
5. Furnace awaits call from thermostat.
1. R and W thermostat contacts close, initiating a call for
heat.
2. Integrated control module performs safety circuit checks.
3. The induced draft blower is energized causing pressure
switch contacts to close. Induced draft blower remains
energized for pre-purge period.
4. Ignitor warm up begins after pre-purge is completed.
5. Gas valve opens at end of ignitor warm up period, deliv-
ering gas to burners to establish ame.
6. The control checks for a signal from the ame sensor
within seven (4) seconds after the gas valve is energized.
Gas will only continue to ow if a ame signal is present.
7. Circulator blower is energized on heat speed following a
xed thirty (30) second blower on delay.
8. Furnace runs, integrated control module monitors safety
circuits continously.
9. R and W thermostat contacts open, allowing the gas valve
to cycle o.
10. Induced draft blower is de-energized following a fteen
(15) -second post purge.
11. Circulator blower is de-energized following a selectable
heat o delay period (90, 120, 150 or 180 seconds).
12. Furnace awaits next call from thermostat.
The adjustable delay-off timing allows the installer to
customize the comfort level.
The normal operational sequence in cooling mode is as
follows:
1. R and Y thermostat contacts close, initiating a call for cool.
2. Integrated control module performs safety circuit checks.
3. Outdoor fan and compressor are energized.
4. Circulator blower is energized on cool speed following a
xed ve (7) second on delay.
5. Furnace circulator blower and outdoor cooling unit
run, integrated control module monitors safety circuits
continuously.
6. R and Y thermostat contacts open, completing the call for
cool.
7. Outdoor fan and compressor are de-energized.
8. Circulator blower is de-energized following a xed forty
ve (65) second cool o delay period.
9. Furnace awaits next call from thermostat.
The normal operational sequence in fan only mode is as
follows:
1. R and G thermostat contacts close, initiating a call for fan.
2. Integrated control module performs safety circuit checks.
3. Circulator blower is energized on .
4. Circulator blower runs, integrated control module monitors
safety circuits continuously.
5. R and G thermostat contacts open, completing the call
for fan.
6. Circulator blower is de-energized.
7. Furnace awaits next call from thermostat.