Mitsubishi Electric PU(H)Y-P250YGM-A, Service Handbook

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[
IX
Troubleshooting ]
1 Although cooling operation
starts with the normal remote
controller display, the capacity
is not enough. 4. Long piping length
The cooling capacity varies great-
ly depending on the pressure
loss.
Confirm that the characteristic of capacity
drop due to piping length.
The piping pressure loss can be assumed
by temperature difference between the heat
exchanger inlet temperature and low pres-
sure saturation temperature.
-> Change the pipe.
5. Piping size is not proper (thin)
6. Insufficient refrigerant amount
Protection works and compressor
frequency does not rise due to
high discharge temperature.
Refer to 1-1. (Compressor frequency does
not rise sufficiently.)Refer to the page on re-
frigerant amount adjustment
7. Clogging by foreign object Check the temperature difference between
in front of and behind the place where a for-
eign object is clogged (e.g. strainer, distrib-
utor). If the temperature drop is large, a
foreign object is clogged.
-> Remove the foreign object inside the
pipe.
8. The indoor unit inlet temperature
is excessively. (Less than 11°C
WB
Check the inlet air temperature and for short
cycling. Change the environment where the
indoor unit is used.
9. Compressor failure
The amount of circulating refriger-
ant decreases due to refrigerant
leak in the compressor.
Check the discharge temperature to deter-
mine if the refrigerant leaks, as it rises if
there is a leak.
10.High/low pressure bypass due to
solenoid valve failure
Refer to the page on troubleshooting of the
solenoid valve.
11.LEV1 malfunction
Sufficient liquid refrigerant is not
be supplied to the indoor unit as
sufficient sub cool cannot be se-
cured due to LEV1 malfunction.
Refer to the page of LEV troubleshooting (9.
[4] -5- ).
It most likely happens when there is little dif-
ference or no difference between TH5 and
TH7.
12.TH5, TH7,TH2, TH8 and 63HS
sensor failure or faulty wiring
LEV1 is not controlled normally.
ΠCheck the thermistor.
ΠCheck wiring.
13.Dirt on the heat exchanger and
short cycle
2 Outdoor unit stops at times
during operation. The first stop is not considered as an
error, as the unit turns to anti-restart
mode for 20 seconds as a prelimi-
nary error.
Error mode
(i) Abnormal high pressure
(ii) Abnormal discharge air
temperature
(iii) Heatsink thermistor failure
(iv) Thermistor failure
(v) Pressure sensor failure
(vi) Over-current break
(vii) Refrigerant overcharge
Note: Frost prevention tripping may
be considered in addition to
the above.
Note: Even the second stop is not
considered as an error
when some specified errors
occur. (eg. The third stop is
considered as an error
when the thermistor error
occurs.)
(1) Check the mode operated in the past
by displaying preliminary error history
on LED display with SW1.
(2) Reoperate the unit to find the mode that
stops the unit by displaying preliminary
error history on LED display with SW1.
Refer to the reference page for each
error mode.
*Display the indoor piping tempera-
ture table with SW1 to check wheth-
er the freeze proof operation runs
properly, and check the tempera-
ture.
Phenomena Cause Check method and remedy