8
3-2 Fault Diagnosis by Symptom
3-2-1 No Power(completely dead)-Initial diagnosis
1) Checklist :
(1) Is input voltage normal? (the rating voltage
±10% range)
(2) Is AC power linked correctly?
(3) Is input voltage of DC regulator IC KA7805 (IC02) normal? (11.5VDC-12.5VDC)
(4) Is output voltage of DC regulator IC KA7805 (IC02) normal? (4.5VDC-5.5VDC)
2) Troubleshooting procedure
Replace PCB
display
Is DC voltage of PCB
display normal?
Remove power cord and plug in again
in approx. 5 seconds
Is operation lamp blinking?
Does operation start when
run/stop button on the remote
controller unit pushed?
Is transmission display of the remote
controller unit blinking?
Is "beep"sound heard from the main
unit?
Is DC voltage of the PCB module
normal?
Are voltages of #40 (compressor),
#43 (4 way valve) and #41 or #42 (out-
door fan) of the micom normal? (5VDC)
Is voltage of #39 (indoor fan) of the
micom normal?
Is voltage at #17 terminal of the Micom normal?
;
0VDC
Is voltage at #16 terminal of the Micom normal?
;
5VDC
Is the input rating ±10%
range applied to the
between #1 and #3 of CN78
•Check linkage between
power cord and
terminal tap
•Check fuse
Is 11.5~12.5VAC appear in
the input side of the DC
regulator IC KA7805(ICO2)?
Refer to replace
PCB Module
YES
NO
YES
NO
YES
YES
YES
NO
YES
YES
YES
DC5V
10ms
10ms
100ms
NO
NO
OK
YES
YES
YES
YES
NO
NO
YES
Normal
Refer to remote control
unit fault diagnosis
Refer to Replace
PCB module.
Is output voltage of ICO2 normal?(DC5V)
Check connections
compressor 4-way
valve, outdoor fan and
indoor fan.
Are voltages at RY71(Compressor)
RY73 (4 way vale) and RY 72 (Outdoor fan)
normal? (DC12V)
Is voltage at SS71(indoor fan)
Replace
RY71, RY73,
RY72 and
SS71
NO
NO
NO
Is voltage output terminal of
D101~D105(IN4007) normal?
Replace ICO2
Check PCB pattern. Refer to
Replace nidule PCB.
Replace IN4007
Replace
micom
Is voltage at #10 terminal of the micom
normal?
Are voltage at #18 and #19 of the
micom normal?
NO
NO
NO
YESNO
NO
NO
YES
OK
Is operation normal?
Replace resonator (X501)
DB98-05109A(1)-1 3/11/02 12:46 PM Page 8
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