Mitsubishi Electric FDT125VNVF Technical Manual page 415

Error code
None
Remote controller:
1. Applicable model
All models
2. Error detection method
3. Condition of Error displayed
4. Presumable cause
Note:
RUN light TIMER light
Indoor
– –
display
Green LED Red LED
Outdoor
– –
control PCB
5. Troubleshooting
Diagnosis
From
previous page
[Unit side]
YES
Does noise/vibration
occur when the cooling/
heating operation is
performed
normally?
NO
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Content
Excessive noise/vibration (2/3)
Are the pipes
contacting the
casing?
NO
Is it heard
continuous hissing or
roaring sound?
NO
Are hissing sounds
heard at the startup or
stopping?
NO
Is blowing sound
heard at the start/stop
of defrosting during
heating?
NO
Is cracking noise
heard during heating
operation?
NO
Hissing noise is
heard during cooling
operation or after
stopping.
NO
- -
'12 • PAC-T-174
Countermeasure
Rearrange the piping to
avoid contact with the
YES
casing.
It is noise/vibration that
is generated when the
refrigerant gas or liquid
flow through inside of
piping of air-conditioner.
YES
It is likely to occur
particularly during cooling
or defrosting in the heating
mode. It is normal.
The noise/vibration occurs
when the refrigerant starts
YES
or stops flowing. It is
normal.
When the defrosting starts
or stops during heating,
the refrigerant flow is
reversed due to switching
4-way valve. This causes
a large change in pressure
YES
which produces a blowing
sound. It may accompany
also the hissing sounds as
mentioned above. They are
normal.
After the start or stop of
heating operation or during
defrosting, abrupt changes
YES
in temperature cause resin
parts to shrink or expand.
This is normal.
It is the sound produced
by the drain pump that
discharges drain from the
indoor unit. The pump
continues to run for 5
YES
minutes after stopping the
cooling operation. This is
normal.
Apply the damper sealant
at places considered to
be the sources such as
the pressure reducing
mechanism (expansion
valve), capillary, etc.