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11-9. How to Check Simply the Main Parts
11-9-1. How to Check the P.C. Board (Indoor Unit)
(1) Operating precautions
1) When removing the front panel or the P.C. board, be sure to shut off the power supply breaker.
2) When removing the P.C. board, hold the edge of the P.C. board and do not apply force to the parts.
3) When connecting or disconnecting the connectors on the P.C. board, hold the whole housing. Do not
pull at the lead wire.
(2) Inspection procedures
1) When a P.C. board is judged to be defective, check for disconnection, burning, or discoloration of the
copper foil pattern or this P.C. board.
2) The P.C. board consists of the following 2 parts
a. Main P.C. board part :
DC power supply circuit (5V, 12V, 15V), Indoor fan motor control circuit, CPU and peripheral circuits,
buzzer, and Driving circuit of louver.
b. Indication unit of infrared ray receiving infrared ray receiving circuit, LED :
To check defect of the P.C. board, follow the procedure described below.
NG
OK
BA
Replace control
board assembly.
Replace
control board.
Replace
compressor.
Check
compressor
winding
resistance.
Diagnosis/Process flowchart Item
Check
Operation
Contents
Check winding resistance
between phases of compres-
sor, and resistance between
outdoor frames by using a
tester.
• Is not grounded.
• Is not short-circuited
between windings.
• Winding is not opened.
Remove connector CN300 of
the outdoor fan motor, turn
on the power supply breaker,
and perform the operation.
(Stops though activation is
prompted.)
Check operation within 2
minutes 20 seconds after
activation stopped.
Summary
→ OK if 10MΩ or more
→ OK if 0.51Ω → 0.57Ω
(Check by a digital tester.)