Mitsubishi Electric MXZ-24UV - E1 Service Manual page 25

Symptom
Display Detecting method
d d 8 8
Frequency drop by current
protection
(d8)
d d 9 9
Frequency drop by overload
protection
(d9)
Frequency drop by high pres-
d d 7 7
sure protection
(d7) Frequency drop by defrosting
in cooling
d d 6 6
Frequency drop by discharge
temperature protection
(d6)
d d 3 3
Frequency drop by high pres-
sure switch protection
(d3)
d d 1 1
Low discharge temperature
protection
(d1)
Symptom
Display Detecting method
e e 7 7
Defrost thermistor abnormality
(E7)
h h 4 4
Power factor detection abnor-
mality
(h4)
Outdoor unit operates. (The compressor operates at reduced frequency.)
Detecting method
When the outdoor unit input current exceeds 22.5 A, the compressor
operates at reduced frequency.
When the compressor load exceeds the specified value, the compres-
sor operates at reduced frequency.
When indoor pipe temperature exceeds 55˚C during heating, the com-
pressor operates at reduced frequency.
When the indoor pipe temperature falls to 6˚C or below during cooling,
the compressor operates at reduced frequency.
When the discharge temperature exceeds 110˚C, the compressor oper-
ates at reduced frequency.
When the high pressure exceeds 2.75MPa (28 kgf/cm
pressor operates at reduced frequency. In addition, the fan speed
changes.
When the state with low discharge temperature of which 50˚C in COOL
and 48.4 or less in HEAT for 20 minutes, the compressor operates con-
tinuously.
Outdoor unit operates.
Detecting method
When a short or open circuit occurs in the defrost thermistor during
heating
* In this case, the compressor continues to operate.
When the compressor power factor cannot be detected
* In this case, the compressor keeps running.
2
-G), the com-
25
Check points
These symptoms do not mean any
abnormality of the product, but check the
following points.
• Air filter clogging.
• Amount of gas.
• Short cycle of indoor/outdoor air flow.
• Amount of gas.
• Outdoor unit air passage.
Check the amount of gas.
• Replace the outdoor controller board.
• Check the contact of LEV board connec-
tors.
Check points
• Defrost thermistor characteristic.
• Contact of P. C. board connectors.
• Compressor wiring.