127
Frequency drop by current
protection
When the outdoor unit input current exceeds 16A(MXZ-18RV) 22.5 A
(MXZ-32RV), the compressor operates at reduced frequency.
These symptoms do not mean any abno
mality of the product, but check the folling-
points.
• Air filter clogging
• Amount of gas
• Short cycle of indoor/outdoor air flow
Display
Detecting method
Detecting method
Check points
Symptom
Outdoor unit operates. (The compressor operates at reduced frequency.)
Frequency drop by overload
protection
When the compressor load exceeds the specified value, the compres-
sor operates at reduced frequency.
Frequency drop by high pres-
sure protection
When indoor pipe temperature exceeds 55˚C during heating, the com-
pressor operates at reduced frequency.
Frequency drop by defrosting
in cooling
When the indoor pipe temperature falls to 6˚C or below during cooling,
the compressor operates at reduced frequency.
Frequency drop by discharge
temperature protection
When the discharge temperature exceeds 115˚C, the compressor oper-
ates at reduced frequency.
Frequency drop by high pres-
sure switch protection
When the high pressure exceeds 2.75MPa (28 kgf/cm
2
-G), the com-
pressor operates at reduced frequency. In addition, the two-way valve
reverses and the fan speed changes.
• Amount of gas
• Outdoor unit air passage
<Only MXZ-32RV>
Frequency drop by low pres-
sure switch protection
When the low pressure falls to 0.05Mpa or below, the compressor oper-
ates at reduced frequency. In addition, the two-way valve opens.
• Ball valve
• LEV operation
• Pipe bending or clogging
• Outdoor control P.C. board
<Only MXZ-32RV>
Low pressure switch protec-
tion
When the low pressure has been 0.05Mpa(0.5 kgf/cm
2
-G) for 5 minutes
or more, the compressor stops and restarts in 3 minutes.
• Check the ball valve.
• Check the pipes for bending or clogging
• Check the LEV operation.
• Replace the outdoor controller board.
Low discharge temperature
protection
When the discharge temperature has been 35˚C or below for 50 min-
utes or more, the compressor stops and restarts operation in 3 minutes.
• Check the amount of gas.
• Replace the outdoor controller board.
• Check the contact of LEV board connec-
tors.
<Only MXZ-32RV>
Compressor stop by thermo-
stat function
When the compressor inner thermostat detects 130˚C or above, the
compressor stops and restarts operation in 3 minutes.
• Check the inverter output. Refer to
G
to
K
.
• Check the compressor.
• Check the amount of gas.
• Check the indoor unit air filter for clogging.
• Check the indoor/outdoor air flow for short
cycle.
Defrost thermistor abnormality
When a short or open circuit occurs in the defrost thermistor during
heating
* In this case, the compressor continues to operate.
• Defrost thermistor characteristic
• Contact of P. C. board connectors
Display
Detecting method
Detecting method
Check points
Symptom
Outdoor unit operates.
Room-A pipe temperature
thermistor abnormality
When a shot or open circuit occurs in the Room-A pipe temperature
thermistor
* In this case, the compressor keeps running.
• Room A pipe temperature thermistor
characteristic
• Contact of P.C. board connectors
Room-B pipe temperature
thermistor abnormality
When a short or open circuit occurs in the Room-B pipe temperature
thermistor
* In this case, the compressor keeps running.
• Room B pipe temperature thermistor
characteristic
• Contact of P.C. board connectors
<Only MXZ-32RV>
Room-C pipe temperature
thermistor abnormality
When a short or open circuit occurs in the Room-C pipe temperature
thermistor
* In this case, the compressor keeps running.
• Room C pipe temperature thermistor
characteristic
• Contact of P.C. board connectors
<Only MXZ-32RV>
Room-D pipe temperature
thermistor abnormality
When a short or open circuit occurs in the Room-D pipe temperature
thermistor
* In this case, the compressor keeps running.
• Room D pipe temperature thermistor
characteristic
• Contact of P.C. board connectors
Power factor detection abnor-
mality
When the compressor power factor cannot be detected
* In this case, the compressor keeps running.
• Compressor wiring
Shell temperature overheat
protection
When the discharge temperature rises to 95˚C or above in single-unit
cooling operation, the outdoor fan speed changes.
• Outdoor unit air passage
• Pipe length
Dry protection
When five degrees or more of temperature difference have been detect-
ed between the indoor main temperature and the auxiliary pipe tem-
perature for 10 minutes, the target discharge temperature is reduced.
This symptom does not mean any abnor-
mality in the product, but check the follow-
ings.
• Amount of gas
• Pipe length
d
d2
2
(d2)
d
d11
(d1)
p
p44
(P4)
d
d8
8
(d8)
d
d9
9
(d9)
d
d77
(d7)
d
d6
6
(d6)
d
d3
3
(d3)
d
d2
2
(d2)
e
e77
(E7)
f
f55
(F5)
h
h6
6
(h6)
p
p2
2
(P2)
h
h44
(h4)
p
p9
9
(P9)
f
f77
(F7)
f
f6
6
(F6)