Check SiUS281811EA
312 Part 6 Service Diagnosis
9. Depress the orange power button to turn off motor.
10. Disconnect power. Disconnect diagnostic tool.
11. Reconnect the 4-wire harness from control board to motor.
Electrical Checks - High Voltage Power Circuits
HIGH VOLTAGE!
Disconnect ALL power before servicing or installing. Multiple power sources may be present.
Failure to do so may cause property damage, personal injury or death.
1. Disconnect power to air handler or modular blower.
2. Disconnect the 5-circuit power connector to the ECM motor.
3. Turn on power to air handler or modular.
Line Voltage now present.
4. Measure voltage between pins 4 and 5 on the 5-circuit connector. Measured voltage should be
the same as the supply voltage to the air handler or modular.
5. Measure voltage between pins 4 and 3. Voltage should be approximately half of the voltage
measured in step 4.
6. Measure voltage between pins 5 and 3. Voltage should be approximately half of the voltage
measured in step 4.
7. If no voltage is present, check supply voltage to air handler or modular blower.
8. Disconnect power to air handler or modular blower. Reconnect the 5-circuit power harness
disconnected in step 2.
Power
Button
Green
LED
Motor
Action
Indication(s)
OFF OFF
Not
Rotating
Confirm 24VAC to UltraCheck-EZ
TM
tool. If 24VAC
is confirmed, diagnostic tool is inoperable.
ON Blinking Rotating Motor and control/end bell are functioning properly.
ON OFF Rotating Replace motor control/end bell.
ON Blinking
Not
Rotating
Check motor (refer to Motor Checks on page 314).
ON OFF
Not
Rotating
Replace motor control/end bell; verify motor (refer
to Motor Checks on page 314).
1
2
3
4
5
Lines 1 and 2 will be connected
for 120VAC Power Connector
applications only
Gnd
AC Line Connection
AC Line Connection
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