112
SERVICING
VARIABLE SPEED (ECM) MOTOR TEST
(Heat Pump Cooling Single-Stage Call)
THERMOSTAT HEAT INPUT(S): R, Y1, O, G
First, low voltage readings are measured with the 16-pin wire
harness disconnected from the motor. A diagram of the har-
ness and pin locations is provided below. Voltage measure-
ment 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 with a heat
pump, the integrated control board has to receive a (Y1) and
(O) signal from the thermostat. Turn the thermostat to the
Cooling 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
bar. Now place a jumper wire between the (R), (Y1), (O) 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(Common) and Pin 12 (R) should read 24 AC volts, Pin
1(Common) and Pin 6 (Y1) or to Pin 9 (O) should ready 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 read-
ings you may have a 16-pin wire harness or integrated con-
trol board problem.
Make sure you have high voltage at the 5-pin connector go-
ing 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)
8 0 VDC Common
O924 VACO = ON
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
R1224 VACR = ON
EM/W2 13 0 VAC EM/W2 = OFF
Y/Y2 14 0 VAC Y/Y2 = OFF
G
(1)
15
≥ 13 VAC
G = ON
Out +
(3)
16 0-3.5 VDC CFM LED
Thermostat Input(s): R, Y1, O, G
Delay
(4)
4
5
Cool
(4)
Adjust
(4)
7
11
Heat
(4)
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