Goodman ACS series Service Instructions Manual page 81

SYSTEM OPERATION
HEATING - Abnormal Operation
(Amana® Brand 80% & 90% Variable Speed Furnaces -
White Rodgers 50V61 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. Check for voltage to the furnace and low volt-
age at the control board. Check for blown fuse on the
control board. If the control determines it has an internal
fault, it enters a locked-out state. Any of the situations
mentioned will cause the diagnostic LED to provide no
signal. The control board should only be replaced only
after all other checks from the Troubleshooting Chart
have been verified.
2. System Lockout. If a flame is not sensed during the
first seven (4) seconds after the gas valve is energized,
the control turns off the gas. There will then be a 30
second delay while the induced draft blower is energized
to purge the heat exchanger. The ignitor will again be
energized and preheated for (20) seconds. The gas valve
will then be energized. If flame is not sensed the gas
valve will be de-energized and another purge will occur
and a third ignitor warm up for (20) seconds will occur.
The control will cycle the gas valve a total of three (3)
times before it determines it cannot establish measur-
able combustion and enters a locked out state. The di-
agnostic 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 for more than 5 seconds and less than (20) seconds
and then back on. It can also be reset by turning off the
electrical disconnect switch to the furnace for a mini-
mum of (5) 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. Low Stage Pressure Switch Stuck Closed. If the con-
trol senses the low stage pressure switch is closed when
the induced draft blower is off, it waits until the fault is
corrected. The diagnostic light code for this problem is
two short flashes followed by a longer pause. The prob-
able cause is either a faulty pressure switch or wiring.
4. Pressure Switch Stuck Open. If, after the induced draft
blower is energized, the pressure switch does not close
within 5 minutes, the control will go into a 1-hour lock-
out. The control will automatically reset from lockout and
restart the ignition sequence. 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,
restricted air intake or flue piping.
5. Open Primary or Auxiliary Limit. If the limit control
opens, the air circulator blower will be turned on until the
limit closes. The induced draft blower will turn on for (15)
seconds, then turn off. The diagnostic light code for this
problem is four short flashes followed 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. Flame Sensed with No Call for Heat. If the control
senses a flame when the gas valve is de-energized, it
will run the air circulation blower and the induced draft
blower continuously with no further furnace operation.
The diagnostic flash code for this is a five flashes. The
probable causes are either a short to ground in flame
sense circuit, miswiring, lingering burner flame or a slow
closing gas valve.
7. Low Flame Sense Signal. If the furnace continues to
operate and the micro-amp signal from the flame sensor
falls below specified level, the diagnostic light code for
this problem will be 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 improper gas pressure or combus-
tion air.
8. 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 continously flash-
ing. The probable cause is either the 115V AC power to
furnace or integrated control module is reversed, the 24V
AC wires to transformer are reversed, or poor unit ground.
9. Check Igniter or No Ground Condition. Check for
broken or improperly connected igniter. Check for proper
ground and correct. The diagnostic light code for this
problem is eight flashes followed by a pause.
10. High Stage Pressure Switch Stuck Open. This con-
dition can occur if the pressure switch hose is blocked
or pinched. Check for blocked flue and/or inlet air pipe.
Blocked drain, weak induced draft blower and malfunc-
tioning pressure switch are possible. The diagnostic
light code for this problem is nine flashes followed by a
pause.
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