Mitsubishi Electric MXZ-3C54VA Service Manual page 67

MXZ-6C120VA
• When heating operation does not work.
1. Disconnect the lead wire leading to the compressor.
2. 3 minutes after turning ON the power supply, start EMERGENCY
OPERATION in HEAT mode.
Is there voltage of 230V AC between pin 1 and
pin 2 at connector CN712?
Yes
Turn OFF the power supply.
Disconnect the connector CN912.
Is there normal resistance
to R.V. coil? (Refer to 11-5.)
Yes
Replace the 4-way valve.
• When cooling operation does not work.
1. Disconnect the lead wire leading to the compressor.
2. 3 minutes after turning ON the power supply, start EMERGENCY
OPERATION in COOL mode.
Is there voltage of 230V AC between pin1 and
pin 2 at connector CN712 ?
Yes
Replace the outdoor control P.C. board.
• When cooling, heat exchanger of non-operating indoor unit frosts.
• When heating, non-operating indoor unit gets warm.
Check of LEV
Turn ON the power supply to the outdoor unit after checking
LEV coil is mounted to the LEV body securely.
Is "click - click" sound heard?
Or, do you feel vibration of LEV coil with your hand?
No
Disconnect the connectors.
CN791: LEV A, CN792: LEV B, CN793: LEV C,
CN794: LEV D, CN795: LEV E, CN796: LEV F,
CN797: LEV M.
Is there normal resistance to LEV coil?
(Refer to 11-5.)
No
Replace LEV coil.
No
No
Replace the R.V. coil.
No
Yes
Is there voltage 230V AC
between the pin 1 and pin 3 at
connector CN711?
Yes
Replace the outdoor control P.C. board.
Replace the 4-way valve.
CN791
CN792
CN793
CN794
CN795
CN796
CN797
Yes
Normal
Replace the outdoor electronic control
P.C. board or the outdoor control P.C. board.
67
MXZ-6C120VA
CN711 Outdoor control P.C. board
CN712
No
Replace the power board.
MXZ-3C/4C/5C MXZ-6C
Outdoor Outdoor
electronic control
control P.C. board
P.C. board