Fujitsu AOUH18LMAS1, Service Manual

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3-3. No operation (Power is on)
Forecast of cause
Setting/ Connection failure
External cause
Electrical components defective
Check point 1. Check indoor and outdoor installation condition
• Indoor unit:
– Check incorrect wiring between indoor unit and remote controller.
– Check if there is an open cable connection.
• Are these indoor unit, outdoor unit, and remote controller suitable model numbers to connect?
-> If there is some abnormal condition, correct it by referring to the installation manual and “DESIGN
& TECHNICAL MANUAL”.
Turn off the power and check correct followings.
• Is there loose or removed communication line of indoor unit and outdoor unit?
Check point 2. Check external cause at indoor and outdoor (Voltage drop or Noise)
• Instant drop: Check if there is a large load electric apparatus in the same circuit.
• Momentary power failure: Check if there is a defective contact or leak current in the power sup-
ply circuit.
• Noise: Check if there is any equipment causing harmonic wave near electric line. (Neon bulb or
electric equipment that may cause harmonic wave)
Check the complete insulation of grounding.
Check point 3. Check wired remote controller and controller PCB
Check voltage at CN2 (terminal 1—3) of UT↔-T→R↓Z2 (Communication kit) (for 18
model). Check voltage at CN12 of main PCB (terminal 1—2) (for 24 model).
(Power supply to remote controller)
• If it is DC 5 V (for 18 model) and DC 12 V (for 24 model), remote controller is
failure. (The controller PCB is normal)
-> Replace remote controller.
• If it is DC 0 V, controller PCB is failure. (Check the remote controller once
again)
-> Replace controller PCB.
Check point 4. Replace main PCB
If check point 1 to 3 do not improve the symptom, change main PCB.
End
3-3. No operation (Power is on)
- (03-54) -
3. Troubleshooting without error code
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