AdvantagePlus Fault Tree Troubleshooting
1706.doc
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You must perform BOTH tests to determine if the blower motor or control board is bad. Unit must PASS both tests
to verify the blower motor is bad; or FAIL one test to determine the main control board is bad.
Things to remember:
A. The main pc control board passes the 120VAC to the motor. There is NOT a direct link to the line voltage
except through this board.
B. If you have 120VAC on plug CN1, you must have 120VAC on the plug CN4 or the pc board is bad.
C. You must perform all tests to determine if the blower motor or pc control board is good or bad.
Continue to next step
Is the blower getting 120
VAC?
Yes
No
Replace control board
The main control board passes the 120VAC from the power source -
there is not a direct link to line voltage except through the main
control board.
1. Measure for 120 VAC on the black and white wires of CN4. You
can verify the 120 VAC on the black and white wires at the blower
motor. If so, then you have power to the blower. If not, replace the
control board.
Replace blower
Is the blower getting DC
control voltage from the
board?
Yes
No
Replace control board
DC voltage is used to signal the blower to turn on and off. This
signal is generated by the control board.
2. Measure for between 2.0 and 8.8 DC volts on the orange (+) and
blue (-) wires at CN2. You can verify the DC voltage on the orange
and blue wires at the blower motor. If so, then you have the proper
signal for the blower to operate. If not, replace the control board.
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