Cooling - Mitsubishi Electric MXZ-2B20NA Service Manual

Indication
No. Symptom
LED1(Red) LED2(Yellow)
17 'Outdoor
unit stops Lighted
and restarts
3 minutes
18
later' is
Lighted 11 times
repeated.
19
Lighted 12 times
20 Outdoor
unit operates
Once
21
Twice
22
3 times
23
4 times
24
5 times
7 times
25 Outdoor
unit
operates
normally.
7 times
8 times
9 times
26 Lighted
NOTE 1. The location of LED is illustrated at the right figure. Refer to 11-7.3.
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
OBH560G
Abnormal point /
Condition
Current sensor
8 times
protection
Communication
protection between
P.C. boards
Zero cross detecting
circuit protection
Primary current
Lighted
protection
High-pressure
protection
Lighted
Defrosting in cooling
Discharge
Lighted temperature
protection
Low discharge
Lighted temperature
protection
Cooling high-
Lighted
pressure protection
High Low
Pressure bypass
valve
Lighted
Cooling evaporating
temperature drop
prevention control
High Low
pressure bypass valve
High pressure protection
control at start-up of
heating operation
Lighted
High Low
pressure bypass
valve
Compressor oil tempering
control at start-up of
heating operation
Cooling evaporating
Lighted temperature
protection
Lighted Inverter check mode
Lighted Normal
0.5-second ON
2.5-second OFF
Condition
After the operation starts, a short or open circuit
is detected in the current sensor when the
compressor is not 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 when the
compressor begins operating.
The primary current exceeds 27A.
The indoor heat exchanger exceeds 100.4°F
during heating.
The indoor heat exchanger falls 37.4°F or below
during cooling.
The discharge temperature exceeds 212°F during
operation.
The frequency of the compressor is kept 58 Hz or
more and the discharge temperature is kept under
122°F (cooling) /104°F (heating) for more than 20
minutes
The outdoor heat exchanger temperature exceeds
129.2°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
becomes less than 53.6°F - 60.8°F* later than that.
* It depends on the difference between the set
temperature and the room temperature.
The room temperature is 75.2°F or more when 1 or
2 unit(s) start(s) the heating operation.
Both the following are true:
• The outside temperature is 28.4°F or less when
the heating operation is started.
• [(Discharge temperature) - (Indoor heat
exchanger temperature)] < 41°F
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 connector of compressor is disconnected.
Inverter check mode starts.
64
Remedy
• Replace the outdoor power P.C. board .
• Check the connecting wire between outdoor
control P.C. board and outdoor power P.C. board.
• Check the connecting wire between 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 indoor fi lters are not clogged.
• Check there is suffi cient refrigerant.
• Check indoor/outdoor unit air circulation
is not short cycling.
• Check refrigerant circuit and refrigerant amount.
• Refer to 11-6. "Check of LEV".
• 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 indoor fi lters are not clogged.
• Check there is suffi cient refrigerant.
• Check indoor/outdoor unit air circulation is short
cycling.
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.
This symptom does not mean any
abnormality of the product.
• Check the connector of the compressor is
correctly connected.
• Refer to 11-6. "How to check inverter/
compressor".
Outdoor control P.C. board (Parts side)
Lighted
0.5-second ON
LED2
LED1