Mitsubishi Electric MXZ-3C54VA, Service Manual

Page: 62 / 270

62
The flashing frequency shows the number of times the LED blinks after every 2.5-second OFF.
(Example) When the flashing frequency is “2”.
ON
OFF
2.5-second OFF
2.5-second OFF
0.5-second ON
0.5-second ON
NOTE 1. The location of LED is illustrated at the right figure. Refer to 11-7.2.
2. LED is lighted during normal operation.
No. Symptom
Indication
Abnormal point /
Condition
Condition Remedy
LED1(Red) LED2(Yellow)
17 'Outdoor
unit stops
and restarts
3 minutes
later' is
repeated. Lighting 8 times
Current sensor
protection
After the operation starts, a short or open
circuit is detected in the current sensor when
the compressor is not operating. • Replace the power board.
18
Lighting 11 times
Communication
protection between
P.C. boards Communication error occurs between the
outdoor control P.C. board and power board
for more than 10 seconds. • Check the connecting wire between outdoor
control P.C. board and power board.
19
Lighting 12 times
Zero cross detecting
circuit protection Zero cross signal cannot be detected when
the compressor begins operating. • Check the connecting wire between outdoor
control P.C. board and power board.
20 Outdoor
unit operates
Once Lighting
Primary current
protection
The primary current exceeds 27A. These symptoms do not mean any
abnormality of the product, but check the
following points.
• Check indoor fi lters are not clogged.
• Check there is suffi cient refrigerant.
• Check indoor/outdoor unit air circulation
is not short cycling.
21
Twice Lighting
High-pressure
protection
The indoor heat exchanger exceeds 38°C during
heating.
Defrosting in cooling
The indoor heat exchanger falls 3°C or below
during cooling.
22
3 times Lighting
Discharge
temperature
protection The discharge temperature exceeds 100°C
during operation. • Check refrigerant circuit and refrigerant
amount.
• Refer to 11-6. "Check of LEV".
23
4 times
Lighting
Low discharge
temperature
protection
The frequency of the compressor is kept 58
Hz or more and the discharge temperature is
kept under 50°C (cooling) /40°C (heating) for
more than 20 minutes • Refer to 11-6. "Check of LEV".
• Check refrigerant circuit and refrigerant
amount.
24
5 times Lighting
Cooling high-
pressure protection
The outdoor heat exchanger temperature
exceeds 54°C during operation. This symptom does not mean any
abnormality of the product, but check the
following points.
• Check indoor fi lters are not clogged.
• Check there is suffi cient refrigerant.
• Check indoor/outdoor unit air circulation is
short cycling.
7 times Lighting
High Low
Pressure bypass
valve
Cooling evaporating
temperature drop
prevention control
During cooling operation, the temperature
of indoor heat exchanger becomes 3°C or
less within 1 hour after the compressor starts
running, or it becomes less than 12°C later
than that. This symptom does not mean any
abnormality of the product, but check the
following points.
• Check indoor fi lters are not clogged.
• Check there is suffi cient refrigerant.
• Check indoor/outdoor unit air circulation is
not short cycling.
8 times Lighting
Cooling evaporating
temperature
protection
During cooling operation, the temperature of
indoor heat exchanger becomes 7°C - 11°C
or less within 1 hour after the compressor
starts running, or it becomes 13°C - 17°C or
less later than that.
* It depends on the difference between the set
temperature and the room temperature.
25 Outdoor
unit
operates
normally.
7 times Lighting
High Low
pressure bypass
valve
High pressure
protection control at
start-up of heating
operation The room temperature is 24°C or more when
1 or 2 unit(s) start(s) the heating operation. This symptom does not mean any
abnormality of the product.
High Low
pressure bypass
valve
Compressor oil
tempering control at
start-up of heating
operation
Both the following are true:
• The outside temperature is -2°C or less
when the heating operation is started.
• [(Discharge temperature) - (Indoor heat
exchanger temperature)] < 5°C
9 times Lighting Inverter check mode
The connector of compressor is
disconnected.
Inverter check mode starts. • Check the connector of the compressor is
correctly connected.
• Refer to 11-6. "How to check inverter/
compressor".
26 Lighting Lighting Normal
Outdoor control P.C. board (Parts side)
LED1
LED2
Lighting