AEX12GRN
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2. Troubleshooting of outdoor unit electric components
4
Compressor check
Measure compressor coil resistance
(for each phase of U, V and W).
Use multi-meter or digital tester capa-
ble of displaying two digits right of the
decimal point (0.01
Ω
).
Resistance value at 20
°
C --- 1.13
Ω
Correct connections at compres-
sor terminals.
Replace compressor.
5
Expansion valve check
Measure expansion valve coil resis-
tance.
Each phase 46
±
3
Ω
(at 20
°
C)
Replace expansion valve.
6
Final check
Turn off power, and connect compres-
sor cords to compressor.
Operate air conditioner.
Measure DC voltage between IPM
pins (31) and (35).
Compressor should operate nor-
mally.
200 VDC or higher.
Replace control PWB.
Replace outdoor unit thermistor.
Replace compressor (in case of
compressor lock).
No
.
Item
Check method
Normal value/condition
Remedy
Does LED light?
NO
YES
YES
NO
Does LED flash?
Normal
NO
YES
NO
YES
NO
YES
NO
YES
Is 230 V applied
between 1 and
N on outdoor
unit terminal
board?
Is voltage between
IPM pins (31) and
(35) 320 V or
higher?
5/ Short-circuit in DC fan motor
Short-circuit in IPM
Short-circuit in diode bridge
Blown fuse
Defective electrolytic capacitor
Wire disconnection, PWB pattern damage
Short-circuit in PAM IGBT (Q5)
Defective switching power supply circuit
Malfunction of 3-terminal regulator IC4, IC1
Short-circuit in expansion valve coil
Malfunction of transistor array IC7
Solder contact or other problems
Malfunction of 3-terminal regulator IC4, IC1
Microcomputer oscillator error
Malfunction of microcomputer reset IC
Malfunction of microcomputer
Malfunction of serial signal circuit
Check wiring between indoor and outdoor units.
Is switching power
supply output of
13 VDC, 15 VDC
produced?
Is 5 VDC output
produced?
Check indoor
unit.