Mitsubishi Electric CMB-WM108V-AA Service Handbook page 188

[ VIII Troubleshooting ]
3. RPM error of the outdoor unit FAN
Motor failure or board failure, or airflow rate de-
crease due to clogging of the heat exchanger
The fan is not properly controlled as the outdoor
temperature cannot be precisely detected by the
temperature sensor.
The fan is not properly controlled as the pressure
cannot be precisely detected by the pressure sen-
sor.
4. Long piping length
The cooling capacity varies greatly depending on the
pressure loss. (When the pressure loss is large, the
cooling capacity drops.)
5. Piping size is not proper (thin)
6. Insufficient refrigerant amount
Protection works and compressor frequency does
not rise due to high discharge temperature.
7. Clogging by foreign object
8. The indoor unit inlet temperature is excessively.
(Less than 15°C [59°F] WB)
9. Compressor failure
The amount of circulating refrigerant decreases due
to refrigerant leak in the compressor.
10. HBC controller LEV3 actuation failure
Sufficient cold water is not supplied as sufficient sub
cool cannot be secured on the HBC controller due to
LEVI, 2, and 3 actuation failure.
11. TH12, TH15 and 63HS1 sensor failure or faulty wir-
ing
LEV3 is not controlled normally.
12. HBC controller valve block actuation failure
Sufficient cold water is not supplied because of the
insufficient water flow rate and coexistence of cold
and hot water on the HBC controller due to valve
block actuation failure.
HWE1708A
Cause Check method and remedy
Refer to the page on troubleshooting of the outdoor
unit fan in outdoor unit service handbook
Refer to 5106 in outdoor unit service handbook
Refer to 1302 in outdoor unit service handbook
Check the piping length to determine if it is contrib-
uting to performance loss.
Piping pressure loss can be estimated from the
temperature difference between the indoor unit
heat exchanger outlet temperature and the satura-
tion temperature (Te) of 63LS. ->Correct the piping.
Refer to 1-1. (Compressor frequency does not rise
sufficiently.)(page 178)
Refer to the page on refrigerant amount
adjustment(page 124)
Check the temperature difference between in front
of and behind the place where the foreign object is
clogging the pipe (upstream side and downstream
side). When the temperature drops significantly, the
foreign object may clog the pipe.
-> Remove the foreign object inside the pipe.
Check the inlet air temperature and for short cy-
cling. Change the environment where the indoor
unit is used.
Check the discharge temperature to determine if
the refrigerant leaks, as it rises if there is a leak.
Refer to the page of LEV troubleshooting
( [4] -1- ).(page 186)
Check the thermistor.
Check wiring.
Refer to the section on valve block fault under
"Troubleshooting." (page 200)
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GB