Mitsubishi Heavy Industries FDT71VNXVD Service Manual page 45

(2) Troubleshooting
Error code
Remote controller: None
1. Applicable model
All models
2. Error detection method
3. Condition of Error displayed
4. Presumable cause
• Poor compression of
compressor
• Faulty expansion valve
operation
Note:
LED Green Red
Content
Indoor Keeps flashing Stays OFF
Outdoor
Keeps flashing Stays OFF
5. Troubleshooting
Diagnosis
Check the indoor unit fan operation.
Check the temperature differnce
between return and supply air.
Is the
temperature differnce
YES
between return and supply air
10-20degC at
cooling?
NO
Is the compressor
operating?
message is displayed (for 3 seconds) when
performing cooling, defrosting and heating
operations from the remote
YES
Is the
compressor rotation
speed low?
YES
Check which control "Determination
control of conpressor rotation speed" or
"Protective control by controlling
compressor rotation speed" is appropriate
to this phenomenon.
(1)
Are the
temperature conditions
of room and outdoor air close
to the rated
conditions?
Note (1) Outdoor: 35°C, Indoor: 27°C
NO
The unit is operating normally but is
operating under the contol for protecting
compressor or other respective parts.
5
-
Operates but does not cool
Does the
heat load increase after
NO
installtion?
YES
Mistake in model selection.
Calculate heat load once more.
NO
" WAIT "
YES
controller.
NO
NO
YES
-
'10 • PAC-SM-137A
Countermeasure
It is normal.
(This unit is designed to
start in the soft start mode
by detecting the under dome
temperature of compressor
when it restart after power
reset.
It is necessary to replace to
higher capacity one or to
install additional unit.
Compressor refrigerant oil
protection control at starting
is activated. For the contents
of control, refer to the
compressor start control of
the microcomputer control
functions.
Compressor may be stopped
by the error detection
control. For the contents of
control, refer to anomalous
stop control by controlling
compressor rotation speed
of microcomputor control
functions.
Inspect the followings.
• Minor clogging of filter
• Minor clogging of heat
exchanger
• Minor short-circuit
• Minor shortage of
refrigerant amount
• Poor compression of
compressor
Considering appropriate
operation control, check
suspicious points.
Inspect the followings for
reference.
• Major clogging of filter
• Major clogging of heat
exchanger
• Major short-circuit
• Major shortage of
refrigerant amount
• Compressor protection ON
• Indoor fan tap
• Valid setting of silent mode