Amana GUIA Series Service Instructions Manual page 80

SYSTEM OPERATION
ABNORMAL OPERATION
(80% or 90% Models with White-Rodgers 50A55 or
Heatcraft HSI-2 Integrated Ignition Control)
The following presents the probable causes of questionable
furnace operation and how to fix them. Look through the
observation window in the blower access door and make a
note of the number of flashes in sequence between pauses.
Next, refer to the Troubleshooting Chart on the following
pages for an interpretation of the LED signals and to the
information in this section for a description of the problem.
1. Internal Control Failure with Integrated Ignition
Control. If the control determines it has an internal fault,
it enters a locked-out state, and the diagnostic light will
light continuously with no flashes. The control should
be replaced.
2. System Lockout. If a flame is not sensed during the
first seven (7) seconds after the gas valve is energized,
the control turns off the gas. There will then be a 60
second delay while the induced draft blower is energized
to purge the heat exchanger. The ignitor will next be
energized and preheated for 27 seconds. The gas valve
will then be energized. If flame is not sensed in seven (7)
seconds the gas valve will be de-energized and another
purge will occur. The control will cycle the gas valve a
total of three (3) times before it determines it cannot
establish measurable combustion and enters a locked
out state. If flame is sensed but lost after ten (10) sec-
onds, the control will recycle this series of three tries
four (4) more times before locking out. The diagnostic
light code for this problem is one short flash followed
by a longer pause. The control can be reset and brought
out of lockout mode by turning the thermostat off and
then back on. It can also be reset by turning off the elec-
trical disconnect switch to the furnace for 30 seconds.
NOTE: The control board will automatically reset one hour
after lockout occurs. If the furnace frequently has to be re-
set, it means that a problem exists that should be corrected.
Refer to Troubleshooting Chart on the following pages for
aid in determining the cause.
3. Pressure Switch Stuck Closed. If the control senses
the pressure switch is closed when the induced draft
blower is off, it waits until the fault is corrected. The di-
agnostic light code for this problem is two short flashes
followed by a longer pause. The probable cause is either
a faulty pressure switch or wiring.
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Rev. 1
4. Pressure Switch Stuck Open. If, after the induced draft
blower is energized, the pressure switch does not close,
the control will keep the induced draft blower on and wait
for the switch to close. The diagnostic light code for this
problem is three short flashes followed by a pause.
The probable causes are either disconnected hose to
the pressure switch, faulty pressure switch or wiring, or
restricted air intake or flue piping.
5. Open Primary or Auxiliary Limit. If the limit control
opens, the air circulator blower and induced draft blower
will be turned on until the limit closes. The diagnostic
light code for this problem is four short flashes fol-
lowed by a pause. The probable cause is either low
conditioned air flow due to dirty filter or resistance in
duct work, faulty limit, faulty blower, or blower speed
set to low.
6. Open Rollout Limit. If the rollout control opens, the air
circulator blower will be energized all the time. The di-
agnostic light code for this problem is five flashes fol-
lowed by a pause. The probable cause is either restricted
flue piping or improper air requirements.
7. Reversed Polarity. If the 115V or 24V AC power leads
are reversed, the furnace will fail to operate. The diag-
nostic light code for this problem is six flashes followed
by a pause. The probable cause is either the 115V AC
power to furnace or integrated control module is reversed,
the 24V AC orange and gray wires to transformer are
reversed, or poor unit ground.
8. Low Flame Sense Signal. (White-Rodgers 50A55 Con-
trol Only). If the furnace continues to operate and the
micro-amp signal from the flame sensor falls below speci-
fied level. The diagnostic light code for this problem is
seven flashes followed by a pause. The probable cause
is either a coated/oxidized sensor, incorrectly positioned
senser in burner flame or lazy burner flame due to im-
proper gas pressure or combustion air.
9. Pressure Switch Opened Five Times During A Single
Call for Heat. If the furnace fails to operate due to pres-
sure switch opening five times during a single call for
heat. The diagnostic light code for this problem is eight
flashes followed by a pause. The probable cause is
either the pressure switch hose is blocked, pinched, or
misconnected, blocked flue or drain system, weak in-
duced draft blower, incorrect pressure switch set point
or faulty pressure switch, or loose or misconnected wir-
ing.