MXZ-5C42NA3 Service Manual

116
No. Symptom
Indication
Abnormal point /
Condition
Condition Remedy
LED1(Red) LED2(Yellow)
18 ‘Outdoor unit
stops and
restarts
3 minutes
later’ is
repeated.
5 times Not lit
High pressure
protection
High pressure is detected with the high pressure
switch (HPS) during operation.
• Check around of gas and the refrigerant circuit.
• Check the stop valve.
The outdoor heat exchanger temperature exceeds
158°F during cooling or the indoor gas pipe tem-
perature exceeds 158°F during heating.
19
6 times Not lit Pre-heating protection Overcurrent is detected during pre-heating.
• Reconnect compressor connector.
• Refer to 12-6.
"How to check inverter/
compressor".
• Check the power module.
20
8 times Not lit Converter protection
A failure is detected in the operation of the con-
verter during operation.
• Replace the outdoor power P.C. board.
21
9 times Not lit
Bus-bar voltage
protection
The bus-bar voltage exceeds 400 V or falls to low
level during compressor operating.
• 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".
22
11 times Not lit
Low out side tempera-
ture protection(cooling)
The ambient became 10.4°F or less.
—
Low out side tempera-
ture protection(Heating)
The ambient became 1.4°F or less. (MXZ-3C24/
3C30/4C36/5C42NA, MXZ-3C24/3C30/4C36/
5C42NA2, MXZ-3C24/3C30/4C36/5C42NA3,
MXZ-3C24/3C30/4C36/5C42NA4)
The ambient became -18°F or less. (MXZ-2C20/
3C24/3C30NAHZ, MXZ-2C20/3C24/3C30NAHZ2,
MXZ-2C20/3C24/3C30NAHZ3, MXZ-2C20/3C24/
3C30NAHZ4)
23
13 times Not lit Outdoor fan motor
A failure occurs 3 consecutive times within 30
seconds after the fan gets started.
• Refer to 12-6.
"Check of outdoor fan motor".
24
14 times Not lit
4-way valve switching
operation
Connector of R.V. coil is disconnected, poorly con-
nected or 4-way valve is faulty.
• Refer to 12-6.
"Check of R.V. coil".
• Check the 4-way valve.
25
Lit 8 times
Current sensor
protection
A short or open circuit is detected in the current
sensor during compressor operating.
• Replace the outdoor power P.C. board.
26
Lit 11 times
Communication
between P.C. boards
protection
Communication error occurs between the outdoor
control P.C. board and outdoor power P.C. board
for more than 10 seconds.
• Check the connecting wire between outdoor con-
trol P.C. board and outdoor power P.C. board.
27
Lit 12 times
Zero cross detecting
circuit protection (Outdoor
power P.C. board)
Zero cross signal cannot be detected while the
compressor is operating.
• Replace the outdoor power P.C. board.
28 Outdoor unit
operates.
Once Lit
Primary current
protection
The input current exceeds 15.0 A (MXZ-2C20NA2,
MXZ-2C20NA3, MXZ-2C20NA4)/18.4 A (MXZ-
3C24/3C30/4C36NA, MXZ-3C24/3C30/4C36NA2,
MXZ-3C24/3C30/4C36NA3, MXZ-3C24/3C30/
4C36NA4)/26.8 A (MXZ-2C20/3C24/3C30NAHZ,
MXZ-5C42NA, MXZ-2C20/3C24/3C30NAHZ2,
MXZ-5C42NA2, MXZ-2C20/3C24/3C30NAHZ3,
MXZ-5C42NA3, MXZ-2C20/3C24/3C30NAHZ4,
MXZ-5C42NA4).
These symptoms do not mean any abnormality of
the product, but check the following points.
• Check if indoor lters are clogged.
• Check if refrigerant is short.
• Check if indoor/outdoor unit air circulation is short
cycled.
29
Twice Lit
High pressure
protection
The indoor gas pipe temperature exceeds 113°F
during heating.
Defrosting in cooling
The indoor gas pipe temperature falls 37.4°F or
below during cooling.
30
3 times Lit
Discharge temperature
protection
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.
• Check refrigerant circuit and refrigerant amount.
• Refer to 12-6.
"Check of LEV".
• Refer to 12-6. "Check of outdoor thermistors".
31
4 times Lit
Low discharge
temperature protection
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.
• Refer to 12-6.
"Check of LEV".
• Check refrigerant circuit and refrigerant amount.
32
5 times Lit
Cooling high pressure
protection
The outdoor heat exchanger temperature exceeds
136.4°F during operation.
This symptom does not mean any abnormality of
the product, but check the following points.
• Check if indoor lters are clogged.
• Check if refrigerant is short.
•
Check if indoor/outdoor unit air circulation is short cycled.
33
7 times Lit
High Low
Pressure bypass
valve
Cooling evaporating
temperature drop
prevention control
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 di󰀨erence between the set
temperature and the room temperature.
(MXZ-2C20/3C24/3C30NAHZ, MXZ-5C42NA,
MXZ-2C20/3C24/3C30NAHZ2, MXZ-5C42NA2,
MXZ-2C20/3C24/3C30NAHZ3, MXZ-5C42NA3,
MXZ-2C20/3C24/3C30NAHZ4, MXZ-5C42NA4)
This symptom does not mean any abnormality of
the product, but check the following points.
• Check the indoor lters are not clogged.
• Check there is su󰀩cient refrigerant.
• Check the indoor/outdoor unit air circulation is not
short cycled.
34
11 times Lit
M-NET communication
error
M-NET adapter P.C. board detects an abnormality
in the communication error.
• Check the connecting wire between M-NET
adapter P.C. board and outdoor control P.C.
board, or terminal block.
OBH702M