Mitsubishi Electric PUHY-(E)P300, Service Handbook

Page: 223 / 302

[
IX
Troubleshooting ]
- 214 -
HWE07010 GB
Both for MA remote controller and M-NET remote controller
1. Phenomena
Although cooling operation starts with the normal remote controller display, the capacity is not enough
2. Cause, check method and remedy
Cause Check method and remedy
1. Compressor frequency does not rise sufficiently.
ΠFaulty detection of pressure sensor.
ΠProtection works and compressor frequency does
not rise due to high discharge temperature
ΠProtection works and compressor frequency does
not rise due to high pressure
ΠPressure drops excessively.
(1) Check pressure difference between the detected
pressure by the pressure sensor and the actual
pressure with self-diagnosis LED.
-> If the accurate pressure is not detected, check
the pressure sensor. (Refer to the page on Trouble-
shooting of Pressure Sensor).
Note: Lower inlet pressure by the low pressure sensor
than the actual pressure causes insufficient capac-
ity.
SW1 setting
(2) Check temperature difference between the evapo-
rating temperature (Te) and the target evaporating
temperature (Tem) with self-diagnosis LED.
Note: Higher Te than Tem causes insufficient capacity.
SW1 setting
Note: Protection works and compressor frequency does
not rise even at higher Te than Tem due to high dis-
charge temperature and high pressure.
At high discharge temperature:
Refer to 1102.(page 159)
At high pressure:
Refer to 1302.(page 161)
2. Indoor unit LEV malfunction Refer to the page of LEV troubleshooting ([4] -5-
).(page 226)
ΠInsufficient refrigerant flows due to LEV malfunc-
tion (not enough opening) or protection works and
compressor frequency does not rise due to pres-
sure drop.
ΠRefrigerant leak from LEV on the stopping unit
causes refrigerant shortage on the running unit.
3. RPM error of the outdoor unit FAN Refer to the page on troubleshooting of the outdoor
unit fan.
Refer to 5106.(page 179)
Refer to 1302.(page 161)
ΠMotor failure or board failure, or airflow rate de-
crease due to clogging of the heat exchanger
ΠThe fan is not properly controlled as the outdoor
temperature cannot be precisely detected by the
temperature sensor.
ΠThe fan is not properly controlled as the pressure
cannot be precisely detected by the pressure sen-
sor.
High pressure sensor
Low pressure sensor
ON
1 2 3 4 5 6 7 8 9 10
ON
1 2 3 4 5 6 7 8 9 10
SW1
SW1
1 2 3 4 5 6 7 8 9 10
Evaporating temperature Te
Target evaporating temperature Tem
ON
1 2 3 4 5 6 7 8 9 10
ON
SW1
SW1