Mitsubishi Electric MXZ-2F33VF4-E1 Service Manual page 189

Indication
No. Symptom
LED1(Red) LED2(Yellow)
20 4 times
21 5 times
22 6 times
23 8 times
'Outdoor unit
stops and
restarts
24 9 times
3 minutes
later' is
repeated.
25 11 times
26 13 times
27 14 times
28 Lit
29 Lit 11 times
30 Lit 12 times
31 Once
32 Twice
33 3 times
34 4 times
35 5 times
Outdoor unit
operates.
36 7 times
OBH790L
Abnormal point /
Condition
Fin temperature
protection
Not lit
P.C. board temperature
protection
High pressure
Not lit
protection
Not lit Pre-heating protection Overcurrent is detected during pre-heating.
Not lit Converter protection
Bus-bar voltage
Not lit
protection
Low outside
Not lit temperature
protection(cooling)
Not lit Outdoor fan motor
4-way valve switching
Not lit
operation
Current sensor
8 times
protection
Communication
between P.C. boards
protection
Zero cross detecting
circuit (Outdoor power
P.C. board)
Primary current
Lit
protection
High pressure
protection
Lit
Defrosting in cooling
Discharge temperature
Lit
protection
Low discharge
Lit
temperature protection
Cooling high pressure
Lit
protection
High Low
Pressure bypass
valve
Cooling evaporating
temperature drop
prevention control
High Low
pressure bypass valve
Lit High pressure
protection control at
startup of heating
operation
High Low
pressure bypass valve
Compressor oil
tempering control at
startup of heating
operation
Condition
The fin temperature exceeds during operation.
The P.C. board temperature exceeds during
operation.
High pressure is detected with the high pressure
switch (HPS) during operation.
The outdoor heat exchanger temperature exceeds
70°C during cooling or the indoor gas pipe tem-
perature exceeds 70°C during heating.
A failure is detected in the operation of the
converter during operation.
The bus-bar voltage exceeds 400 V or falls to
low level during compressor operating.
The ambient became -12°C or less.
A failure occurs 3 consecutive times within
30 seconds after the fan gets started.
Connector of R.V. coil is disconnected, poorly
connected or 4-way valve is faulty.
A short or open circuit is detected in the current
sensor during compressor operating.
Communication error occurs between the out-
door 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 13.6 A (MXZ-2F53VFHZ/
VFHZ2)/ 15 A (MXZ-3F54/3F68/4F72VF/VF2/
VF4/4F80VF2/VF3/VF4)/18.4 A (MXZ-
4F83/5F102VF/VF2)/26.8A MXZ-6F120VF2,MXZ-
6F122VF)/25 A (MXZ-4F83VFHZ/VFHZ2).
The indoor gas pipe temperature exceeds
45°C during heating.
The indoor gas pipe temperature falls 3°C or
below during cooling.
The frequency of the compressor is kept 80 Hz
or more and the discharge temperature is kept
under 50°C(COOL mode)/40°C(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 39°C for more than 20 minutes.
The outdoor heat exchanger temperature
exceeds 58°C during operation.
MXZ-3F54/3F68/4F72VF/VF2/VF3/4F80VF2/VF3/
VF4
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 - 16°C* later than that.
* It depends on the difference between the set
temperature and the room temperature.
MXZ-6F120VF2, MXZ-6F122VF, MXZ-4F83VFHZ/
VFHZ2
The room temperature is 24°C or more when
1 or 2 unit(s) start(s) the heating operation.
MXZ-6F120VF2, MXZ-6F122VF, MXZ-4F83VFHZ
/VFHZ2
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
189
Remedy
•Check refrigerant circuit and refrigerant amount.
•Refer to 12-6. "Check of outdoor fan motor".
• Check around of gas and the refrigerant circuit.
• Check the stop valve.
• Reconnect compressor connector.
• Refer to 12-6. "How to check inverter/
compressor".
• Check the power module.
• Replace the outdoor power P.C. board.
• Check the voltage of power supply.
• Replace the outdoor power P.C. board or the out-
door control P.C. board.
• Refer to 12-6. "Check of bus-bar voltage".
—
• Refer to 12-6. "Check of outdoor fan motor".
• Refer to 12-6. "Check of R.V. coil".
• Check the 4-way valve.
• Replace the outdoor power P.C. board.
• Check the connecting wire between outdoor control
P.C. board and outdoor power P.C. board.
• Replace the outdoor power P.C. board.
These symptoms do not mean any abnormality of the
product, but check the following points.
• Check if indoor filters 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 12-6. "Check of LEV".
• Refer to 12-6. "Check of outdoor thermistors".
• Refer to 12-6. "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 filters 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 filters are not clogged.
• Check there is sufficient refrigerant.
• Check the indoor/outdoor unit air circulation is not
short cycled.