Mitsubishi MUZ-A18YV Service Manual page 38

• When cooling, heat exchanger of non-operating indoor unit frosts.
• When heating, non-operating indoor unit get warm.
D D Check of LEV
Start
Turn on 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 the LEV coil with a hand?
No
Disconnect the connector CN795.
Is there normal resistance to LEV coil?
No
Replace the LEV coil.
When OPERATION INDICATOR lamp flashes 5-time.
• When heating, room does not get warm.
• When cooling, room does not get cool.
E E Check of inverter/ compressor
Start
Disconnect the terminal of the compressor. 3 minutes after turning on the power supply, start
EMERGENCY OPERATION.
Measure the voltage between each
lead wire leading to the compressor.
U (BLK) - V (WHT)
V (WHT) - W (RED)
W (RED) - U (BLK)
Output voltage
COOL: 150V(48Hz) HEAT: 170V(64Hz)
Is voltage output? W
Yes
Is output balanced?
Yes
Is the input voltage to the outdoor electronic
control P.C. board 370V or more?
Yes
Turn off power supply of indoor and outdoor unit,
and measure the compressor winding resistance
between the compressor terminals.
Is the resistance between each terminal normal?
Yes
Reconnect the lead wire of compressor, and turn on
power supply to indoor and outdoor unit.
3 minutes later, starts EMERGENCY OPERATION.
Clarify the causes by counting time until the inverter stops.
0 to 10 seconds: compressor rare short
10 to 60 seconds: compressor lock
60 seconds to 5minutes: refrigerant circuit defective
5 minutes or more: normal
LED display: LED1
Lighting
6 time
LED display:
W • After the outdoor fan starts running, wait for 1 minutes or more before
measuring the voltage.
• The output voltage values have the tolerance of i20%.
No
No
No
LED2
Lighting
Goes out
Yes
Normal
Yes
Replace the outdoor electronic
control P.C. board.
LED1
Lighting
Lighting
Twice
Replace the power board.
No
Replace the
compressor.
38
LED2
Lighting
Twice
Goes out