Mitsubishi Electric MSZ-LN-VG Series Service Manual page 113

MXZ-3F54VF/3F68VF/4F72VF
MXZ-3F54VF2/3F68VF2/4F72VF2/4F80VF2
MXZ-3F54VF3/3F68VF3/4F72VF3/4F80VF3
• 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 220 - 230 - 240 V AC
between pin1 and pin2 at connector CN712?
Yes
Turn OFF the power supply.
Disconnect the connector CNAC2.
Is there normal resistance
to R.V. coil? (Refer to 12-5.)
Yes
Replace the 4-way valve.
• 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 220 - 230 - 240 V AC between
pin1 and pin2 at connector CN712?
Yes
Replace the outdoor control P.C. board.
OBH790D
Is there voltage 220 - 230 - 240 V AC
No
between the pin1 and pin3 at
connector CNAC?
No
Replace the R.V. coil.
No
Yes
Replace the outdoor
control P.C. board.
Replace the 4-way valve.
113
Connector MXZ-3F, 4F
CNAC Outdoor control
CN712 P.C. board
Outdoor power
CNAC2
P.C. board
No Replace the outdoor
power P.C. board.