Troubleshooting - Mitsubishi Electric MXZ-18NV Service Manual

11

TROUBLESHOOTING

11.1 Cautions on troubleshooting
11.1.1 Before troubleshooting, check the followings :
1) Check the power supply voltage.
2) Check the indoor / outdoor connecting wire for mis-wiring.
11.1.2 Take care the followings during servicing.
1) Before servicing the air conditioner,be sure to first turn off the remote controller to stop the main unit,and then after
confirming the horizontal vane is closed,turn off the breaker.
2) When removing the P.C. board, hold the edge of the board with care NOT to apply stress on the components.
3) When connecting or disconnecting the connectors, hold the housing of the connector, DO NOT pull the lead wires.
11.1.3 Troubleshootina procedure
1) First, check if the POWER LAMP on the indoor unit is flashing to indicate an abnormality. To make sure, check the
abnormality indication for 2 or 3 times before starting service work.
2) If the P.C. board is supposend to be defective, check the copper foil pattern for disconnection and the components
for bursting and discoloration.
3) When troubleshooting, refer to the flow chart and the check table .
11-2 Troubleshooting procedure
Single blink
Causes in the indoor/outdoor unit
• Incorrect wiring
• Serial signal error
Serial signal
(Page 42)
See note 1
NOTE1:In case of serial signal
error, the mis-wiring
indication will apper by
turning the power off and
turning it back on.
NOTE2:Enclosed by the
broken line are the indoor
unit related parts.
The indoor unit will
not respond to the
remote controller.
Remote controller
and receiver board.
Two blinks
2.5 second OFF
Three blinks
2.5 second OFF
Causes in the indoor unit.
• Indoor fan motor abnormality.
Pipe temperature thermistor
abnormality.
• Room temperature thermistor
abnormality.
• Check the indoor/
• Pipe temperature
outdoor connecting
thermistor
wiring.
• Room temperature
• Check the outdoor
thermistor
power supply.
Inverter
Compressor
Transistor module
A to E
See page 44,45.
Compressor
See page 44,45.
J Power supply
Operation start
The indoor unit will not respond to the remote
The operation indicator
controller. In addition, the operation
(on the left-hand
indicator (on the left-hand side)will not
side) is blinking
blink even if the emergency run switch is
pressed.
Indoor controller
Causes in the outdoor unit
• Outdoor thermistor
abnormality.
Indoor fan
motor
G 4-way
A to E
value coil.
See page 46.
See page 47.
Outdoor
board
board
Six blinks
2.5 second OFF
Seven blinks
2.5 second OFF
Causes in the outdoor unit
• Outdoor control
system error
F Outdoor
thermistor
See page 46.
Linear H Outdoor fan
• High
expansion motor.
pressure
valve
switch See page 47.
Only
MXZ-32NV
• Low
pressure
switch
• Compressor
thermostat
39