126
SERVICING
a. BEFORE replacing the ECM motor assembly or the
end bell, first check the motor with a GE TECMate
PRO tester. If the motor runs with the tester, the
motor is good. To check the end bell, see the previ-
ous variable speed testing section of this manual be-
fore replacing the end bell.
b. The two-stage variable speed furnaces should have
120 Volts at the motor at all times, even without a
call for cooling or heating. These motors receive their
operational signals (24 Volts) through the 16-pin wir-
ing harness, connected between the motor and inte-
grated control board. NOTE: For complete trouble-
shooting information on units using the ECM/ICM
blower motors, refer to the servicing section - Check-
ing Air Circulator Blowers (S-16B and S-16C) in this
service manual.
Goodman® and Amana® Distinctions™ Brand 80% and
90% Single-Stage (GDS8, GHS8, GMS8, GCS9, GMS9,
GMS95, DDS8, DHS8, DMS8, DCS9, DMS9)
NOTE: The models above use White-Rodgers 50A55-
289 ignition control board.
L
INE VOLTAGE NOW PRESENT
WARNING
These tests must be completed within a given time frame
due to the operation of the ignition control.
1. Check for 120 volts from Line 1 (Hot) to Line 2 (Neutral)
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 terminal on the ignition
control. No voltage. Check transformer, room thermo-
stat, and wiring.
If you have 24 volts coming off the transformer but re-
ceive approximately 13 volts on the terminal board be-
tween (C) and (R), check for blown fuse.
3. Check for 120 volts to the induced draft blower by mea-
suring voltage between Pin 1 (on the 2-pin connector)
and Line (Neutral) on the control board. No voltage, re-
place 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 Pin 2 (on the 2-pin connector) and Line (Neu-
tral) on the control board. No voltage, check pressure
switch.
5. After the ignitor warmup time, begin checking for 24 volts
to the gas valve. Voltage will be present for seven sec-
onds only if proof of flame has been established.
B18099-26
ON
1
2
E17
K2
ST4
DS2 DS1
S1
ST3
E16
E32
E31
E27
E28
E18
E14
E13
E20
E11
E10
E9
E7
E8
DS2
HEAT-H
COOL-H
DS1
2
ONOFF
4
3
1
LINE NEUTRAL
G
TWIN Y W R C
G
TWIN
RW
YC
W125
EAC-H XFMR-H
HUM-H
PARK PARK
LINE-H
0130F00005
GDS8, GHS8, GMS8, GCS9, GMS9, GMS95, DDS8,
DHS8, DMS8, DCS9, DMS9)
(WR50A55-289)
Goodman® 80% and 90% Two-Stage (GMV8, GCV9,
GMV9, GMV95)
NOTE: The models above use White-Rodgers 50V51-289
ignition control board.
1. Check for 120 volts from Line 1 (Hot) to Line 2 (Neutral)
at the ignition control. No voltage, check the door switch
connections and wire harness for continuity.
2. Check for 24 volts from W1 to C terminal on the ignition
control. No voltage. Check transformer, room thermo-
stat, and wiring.
If you have 24 volts coming off the transformer but re-
ceive approximately 13 volts on the terminal board be-
tween (C) and (R), check for blown fuse.
3. Check for 120 volts to the induced draft blower (low-
stage) by measuring voltage between Pin 3 and Pin 4
(on the 5-pin connector) located on circuit board. No
voltage, check for loose connection in the 5-pin connec-
tor or replace ignition control.
Check for 120 volts to the induced draft blower (high-
stage) by measuring voltage between Pin 2 and Pin 4
(on the 5-pin connector) located on circuit board. No
voltage, check for loose connection in the 5-pin connec-
tor, no call for high stage heat or replace ignition con-
trol.
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