Mitsubishi Electric MXZ-2C20NA2 Service Manual page 122

The cooling operation or heating operation does not operate.
Check of R.V. coil
• 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 208/230 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 208/230 V AC between pin1
and pin2 at connector CN712?
Yes
Replace the outdoor control P.C. board.
OBH702N
No
Replace the R.V. coil.
No
No
Is there voltage 208/230 V AC
between the pin1 and pin3 at
connector CNAC?
Yes
Replace the outdoor
control P.C. board.
Replace the 4-way valve.
122
CNAC Outdoor control
CN712 P.C. board
Outdoor power
CNAC2
P.C. board
Replace the outdoor
power P.C. board.
No