When Cooling, Heat Exchanger Of Non-Operating Indoor Unit Frosts/When Heating, Non-Operating Indoor Unit Get Warm; When Heating, Room Does Not Get Warm/When Cooling, Room Does Not Get Cool - Mitsubishi Electric MSC-A07WV Service Manual

• When cooling, heat exchanger of non-operating indoor unit frosts.
• When heating, non-operating indoor unit get warm.
M M 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
(CN771: unit A, CN772: unit B), and measure the
resistance of LEV coil to check the integrity.
No
Replace the LEV coil.
• When heating, room does not get warm.
• When cooling, room does not get cool.
N N Check of inverter/ compressor
Start
Disconnect the connector to the compressor at terminals. 3 minutes after turning on the power
supply, start EMERGENCY OPERATION.
Measure the voltage between each
connector leading to the compressor.
U (BLK) - V (WHT)
V (WHT) - W (RED)
W (RED) - U (BLK)
Output voltage
COOL: 150V(58Hz), HEAT: 150V (58Hz)
Is voltage output? W1
Yes
Is output balanced?
Yes
Turn off power supply of indoor and outdoor unit,
and measure the compressor winding resistance
between the compressor terminals.
Is there resistance of 0.53" to 0.66" between
the each terminals?
Yes
Return the lead wire of compressor to former, and
turn on power supply to indoor and outdoor unit.
Three minutes later, start 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:
<MXZ-A18WV>
<MXZ-A18WV>
W1 • After the outdoor fan starts running, wait for 1 minutes or more before
measuring the voltage.
• The output voltage values in the above table have the tolerance of i20%.
No
No
LED1
Lighting
6 time
Yes
Normal
Yes
Replace the outdoor electronic
control P. C. board
LED display:
Replace the outdoor electronic
control P. C. board
Replace the
No
compressor.
121
LED2
Lighting
Goes out
LED1 LED2
Lighting Lighting
Lighting Twice
Twice Goes out