Amana GUIA Series Service Instructions Manual page 138

SERVICING
The ignition control is a combination electronic and electro-
mechanical device and is not field repairable. Complete unit
must be replaced.
The White-Rodgers 50A50 or 50A51 and the Heatcraft HSI
1-1A or HSI-2 ignition controls, control all furnace opera-
tions including blower operation in air conditioning. Blower
time delays are controlled by the ignition control, see Circu-
lator Blower Timings section in this manual for blower delay
information.
WARNING
LINE VOLTAGE NOW PRESENT.
These tests must be completed within a given time frame
due to the operation of the ignition control. Refer to Sequence
of Operation section of this manual for corresponding timing
charts.
The ignition control is capable of diagnosing many furnace
failures to speed troubleshooting. A flashing red or green
diagnostic indicator light on the control flashes a code for
any discovered failures.
When the control is powered up normally the light will flash
once for about one second. This can be used to test for 120
volts and 24 volts to the control since both must be present
for the light to flash. If this step fails, check for 120 volts to
the control and check the transformer and its associated
wiring. If this step is successful give the control a call for
heat and wait five (5) seconds or until the furnace goes into
lockout. If the control detects a failure it will now be shown
on the diagnostic indicator light. Refer to the Abnormal Op-
eration section in the Sequence of Operation section of this
manual for more detail on failure codes.
The indicator light may be viewed by looking through the
sight glass in the blower compartment door. If the blower
compartment door is removed, failure to hold the door switch
closed while removing the blower compartment door will re-
sult in the loss of the stored failure code. In most cases
recycling the ignition control will result in the same failure
code originally displayed.
1. Check for 120 volts from Line 1 ( BK-6 wire on GUIA,
GCIA, GUIC, GCIC, GUID, GUIS, GCIS and GUIV mod-
els or BK-4 wire on GUCA, GCCA, GUVA and GUSA
models) to line 2 neutral ( WH-33 wire on GUIA, GCIA,
GUIC, GCIC, GUID, GUIS, GCIS and GUIV models or
WH-5 wire on GUCA, GCCA, GUVA and GUSA mod-
els) at the ignition control. No voltage - check the door
switch connections and wire harness for continuity.
2. Check for 24 volts from W to C at the thermostat con-
nections on the ignition control. No voltage - check trans-
former, room thermostat, and wiring.
3. Check for 120 volts to the induced draft blower by mea-
suring voltage between terminals IND ( VT-55 wire on
GUIA, GCIA, GUIC, GCIC and GUID models, or BK
and RD wires on GUIS, GCIS and GUIV models, or
138
Rev. 1
BK-3 wire on GUCA and GCCA models, or RD-15 and
BK-3 wires on GUVA and GUSA models) and neutral.
No voltage - replace ignition control.
4. If voltage is present in Steps 1 through 3 and the in-
duced draft blower is operating, check for 120 volts to
the ignitor during the preheat cycle. Measure voltage
between terminals IGN ( RD-22 wire on GUIA, GCIA,
GUIC, GCIC, GUID, GUIS, GCIS and GUIV models, or
RD-2 wire on GUCA, GCCA, GUVA and GUSA mod-
els) and neutral. No voltage - check pressure switch.
5. After the ignitor warmup time (see notes below), begin
checking for 24 volts to the gas valve. Voltage will be
present for seven seconds only if proof of flame has
been established.
a. On GUIA, GCIA, GUIC, GCIC and GUID models:
Measure voltage from Pin 9 MV/M1 terminal ( GY-47
wire) to Pin 12 C/C2 terminal ( BR-21 wire) on the
ignition control 12 Pin connector. No voltage - replace
ignition control.
b. On GUIS, GCIS and GUIV models: Measure voltage
from either Pin 7 PM terminal ( GY-47 wire) or Pin 1
HI terminal ( YL-11 wire) to Pin 8 C terminal ( BR-21
wire) on the ignition control 12 Pin connector. No volt-
age - replace ignition control.
c. On GUCA and GCCA models: Measure voltage from
Pin 9 C2 terminal (BR-13 wire) to Pin 12 M1 terminal
(GY-12 wire) on the ignition control 12 Pin connec-
tor. No voltage - replace ignition control.
d. On GUVA and GUSA models: Measure voltage from
either Pin 7 PM terminal ( GY-12 wire) or Pin 2 HI
terminal ( YL-20 wire) to Pin 8 C terminal ( BR-13 wire)
on the ignition control 12 Pin connector. no voltage -
replace ignition control.
IMPORTANT: The GUCA, GCCA, GUSA and GUVA model
furnaces have a "Coil Cover Pressure Switch" in series with
the M1 side of the gas valve.
NOTE: The White-Rodgers 50A55 control has an adap-
tive alogrithm that adjusts the duration of ignitor warmup
for the purpose of extending igniter life. Following applica-
tion of power, the warmup time will be 17 seconds for the
first 64 successful ignitions. Each subsequent warmup time
will be decreased by 1 second until flame fails to be achieved
(resulting in a retry) or until the minimum of 5 seconds is
achieved.
NOTE: The Heatrcraft HSI-2 ignition control has an initial
ignitor warmup time of 7 seconds. In the event of a retry,
the warmup time will be increased by two seconds and that
duration will remain effective until another retry. In which case,
the warmup time is again increased by two seconds but
never more than 11 seconds. At the end of the heat cycle,
the warmup time is reset back to the minimum time setting.
NOTE: The White-Rodgers 50M61 and 50V61 ignition
controls have an initial ignitor warmup time of 20 seconds.
These controls have a built-in learning routine that gradu-