SERVICING
111
VARIABLE SPEED (ECM) MOTOR TEST
(Cooling Two-Stage Call)
THERMOSTAT HEAT INPUT(S): R, Y1, Y2, G
First, low voltage readings are measured with the 16-pin
wire harness disconnected from the motor. A diagram of
the harness and pin locations is provided below. Voltage
measurement is AC or DC as specified in the chart below
under the (Volts) column. Set your voltage meter to the
proper AC or DC reading as requested below.
ECM Motor Not Coming On
In order for the cooling fan speed to operate, the integrated
control board has to receive a (Y1) and (Y2) signal from
the thermostat. Turn the thermostat to the Cooling two-
stage position. If the fan will not run, verify 24 volts on the
integrated control boards low voltage terminal strip at (C)
and (R) with your volt meter. If you have 24 volts, remove
thermostat wires from the integrated control boards
terminal strip. Now place a jumper wire between the (R),
(Y1), (Y2) and (G) terminal on the control board. If the
motor now operates then you have a problem in the
thermostat or thermostat cable. If the motor does not
operate, with the terminals above jumped out, unplug the
16-pin harness from the ECM motor. Set volt meter to
read AC volts. Place your voltage meter on Pin 1(Com-
mon) and Pin 12 (R) should read 24 AC volts, Pin 1(Com-
mon) and Pin 6 (Y1) and to Pin 14 (Y/Y2) should read 24
AC volts. Finally, check between Pin 1(Common) and Pin
15 (G), you should read 13 AC volts.
You MUST have all of these low voltage readings before
the ECM motor will come on. If you DO NOT have these
readings you may have a 16-pin wire harness or integrated
control board problem.
Make sure you have high voltage at the 5-pin connector
going to the motor as discussed earlier.
We highly recommend using the GE TECMate PRO™
model ECM motor tester. This low cost test instrument
will verify whether the motor itself is good.
ADJUST +/-
Y 1
COOL
COMMON 2
COMMON 1
OUT +
EM HT/W2
24VAC (R)
BK/Pwm (Speed)
O (Rev Valve)
8
16
CONTROL CONNECTOR
"Motor Half“
(Viewed from connector end)
(1) This input must be active for motor to operate.
(2) 0 VAC indicates humidistat is calling for dehumidification.
(3) These two pins form an output circuit that powers the CFM LED on the ignition control or interface board.
(4) Dipswitch settings determine measure voltage.
(5) Voltage is measured with 16-wire harness disconnected from motor. Voltage measurement is AC or DC as specified in the chart.
Description Pin
Volts
(5)
Signal Indicates
Com, C1 1 0 VAC Common
W/W1 2 0 VAC W1 = OFF
Com, C2 3 0 VAC Common
0 VAC Delay Tap = A
≥
10 VDC
Delay Tap = B
≤
-10 VDC
Delay Tap = C
24 VAC Delay Tap = D
0 VAC Cool Tap = A
≥ 10 VDC
Cool Tap = B
≤ -10 VDC
Cool Tap = C
24 VAC Cool Tap = D
Y1 6 24 VAC Y1 = ON
0 VAC Adjust Tap = A
≥
10 VDC
Adjust Tap = B
≤ -10 VDC Adjust Tap = C
24 VAC Adjust Tap = D
Out -
(3)
80 VDC Common
O90 VACO = OFF
Bk/PWM
(2)
10 24 VAC No Dehumidification
0 VAC Heat Tap = A
≥
10 VDC
Heat Tap = B
≤
-10 VDC
Heat Tap = C
24 VAC Heat Tap = D
R 12 24 VAC R = ON
EM/W2 13 0 VAC EM/W2 = OFF
Y/Y2 14 24 VAC Y/Y2 = ON
G
(1)
15
≥ 13 VAC
G = ON
Out +
(3)
16 0-3.5 VDC CFM LED
Thermostat Input(s): R, Y1, Y2, G
Delay
(4)
4
5
Cool
(4)
11
Heat
(4)
Adjust
(4)
7
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