Mitsubishi Electric MXZ-3C30NA Service Manual page 73

Indication
No. Symptom
LED1(Red) LED2(Yellow)
21 'Outdoor unit
stops and
restarts
3 minutes
11 times
later' is
repeated.
22
13 times
23
Lighted
24
Lighted
25
Lighted
26 Outdoor unit
operates.
Once
27
Twice
28
3 times
29
4 times
30
5 times
31
7 times
32
11 times
33 Outdoor
unit
operates
normally.
7 times
34
8 times
35
9 times
36 Lighted
NOTE: 1. The location of LED is illustrated at the right figure. Refer to 11-7.1.
2. LED is lighted during normal operation.
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
2.5-second OFF
OFF
OBH702E
Abnormal point / Con-
dition
Low out side tempera-
ture protection(cooling)
Not lighted
Low out side tempera-
ture protection(Heating)
Not lighted Outdoor fan motor
Current sensor protec-
8 times
tion
Communication
11 times between P.C. boards
protection
Zero cross detecting
12 times
circuit protection
Primary current protec-
Lighted
tion
High pressure protec-
tion
Lighted
Defrosting in cooling
Discharge temperature
Lighted
protection
Low discharge
Lighted
temperature protection
Cooling high pressure
Lighted
protection
High Low
Pressure bypass
valve
Lighted
Cooling evaporating
temperature drop
prevention control
M-NET communication
Lighted
error
High Low
pressure bypass valve
High pressure protec-
tion control at startup of
heating operation
Lighted
High Low
pressure bypass valve
Compressor oil temper-
ing control at startup of
heating operation
Cooling evaporating
Lighted temperature
protection
Lighted Inverter check mode
Lighted Normal
0.5-second ON
2.5-second OFF
Condition
The ambient became 10.4°F or less.
The ambient became 1.4°F or less. (MXZ-3C24/
3C30/4C36/5C42NA, MXZ-3C24/3C30/4C36/
5C42NA2)
The ambient became -18°F or less. (MXZ-2C20/
3C24/3C30NAHZ, MXZ-2C20/3C24/3C30NAHZ2)
A failure occurs 3 consecutive times within 30
seconds after the fan gets started.
A short or open circuit is detected in the current
sensor during compressor operating.
Communication error occurs between the outdoor
control P.C. board and outdoor power P.C. board
for more than 10 seconds.
Zero cross signal cannot be detected while the
compressor is operating.
The input current exceeds 18.4 A (MXZ-3C24/
3C30/4C36NA, MXZ-3C24/3C30/4C36NA2)/
26.8 A (MXZ-2C20/3C24/3C30NAHZ, 5C42NA,
MXZ-2C20/3C24/3C30NAHZ2, MXZ-5C42NA2).
The indoor gas pipe temperature exceeds 113°F
during heating.
The indoor gas pipe temperature falls 37.4°F or
below during cooling.
The frequency of the compressor is kept 80 Hz or
more and the discharge temperature is kept under
122°F(COOL mode)/104°F(HEAT mode) for more
than 40 minutes.
The frequency of the compressor is kept 80 Hz or
more and the discharge temperature is kept under
102.2°F for more than 20 minutes.
The outdoor heat exchanger temperature exceeds
136.4°F during operation.
During cooling operation, the temperature of indoor
heat exchanger becomes 37.4°F or less within 1
hour after the compressor starts running, or it be-
comes less than 53.6°F - 60.8°F* later than that.
* It depends on the difference between the set
temperature and the room temperature.
(MXZ-2C20/3C24/3C30NAHZ, MXZ-5C42NA,
MXZ-2C20/3C24/3C30NAHZ2, MXZ-5C42NA2)
M-NET adapter P.C. board detects an abnormality
in the communication error.
The room temperature is 75.2°F or more when 1 or
2 unit(s) start(s) the heating operation.
(MXZ-2C20/3C24/3C30NAHZ, MXZ-5C42NA,
MXZ-2C20/3C24/3C30NAHZ2, MXZ-5C42NA2)
Both the following are true:
• The outside temperature is 28.4°F or less when
the heating operation is started.
• [(Discharge temperature) - (Indoor heat exchang-
er temperature)] < 9°F
(MXZ-2C20/3C24/3C30NAHZ, MXZ-5C42NA,
MXZ-2C20/3C24/3C30NAHZ2, MXZ-5C42NA2)
During cooling operation, the temperature of
indoor heat exchanger becomes 44.6°F - 51.8°F*
or less within 1 hour after the compressor
starts running, or it becomes 48.2°F - 62.6°F* or
less later than that.
* It depends on the indoor unit type/model or the
difference between the set temperature and the
room temperature.
The unit is operated with emergency operation
switch.
—
0.5-second ON
73
Remedy
—
• Refer to 11-6. "Check of outdoor fan motor".
• Replace the outdoor power P.C. board.
• Check the connecting wire between outdoor con-
trol P.C. board and outdoor power P.C. board.
• Check the connecting wire among outdoor control
P.C. board and outdoor power P.C. board.
These symptoms do not mean any abnormality of
the product, but check the following points.
• Check if indoor fi lters are clogged.
• Check if refrigerant is short.
• Check if indoor/outdoor unit air circulation is short
cycled.
• Check refrigerant circuit and refrigerant amount.
• Refer to 11-6. "Check of LEV".
• Refer to 11-6. "Check of outdoor thermistors".
• Refer to 11-6. "Check of LEV".
• Check refrigerant circuit and refrigerant amount.
This symptom does not mean any abnormality of
the product, but check the following points.
• Check if indoor fi lters are clogged.
• Check if refrigerant is short.
• Check if indoor/outdoor unit air circulation is short cycled.
This symptom does not mean any abnormality of
the product, but check the following points.
• Check the indoor fi lters are not clogged.
• Check there is suffi cient refrigerant.
• Check the indoor/outdoor unit air circulation is not
short cycled.
• Check the connecting wire between M-NET
adapter P.C. board and outdoor control P.C.
board, or terminal block.
This symptom does not mean any abnormality of
the product.
—
—
Outdoor control P.C. board
(Parts side)
LED1 LED2
Lighted