Mitsubishi Heavy Industries FDT71VNXVD Service Manual page 49

Error code
Remote controller: None
1. Applicable model
All models
2. Error detection method
3. Condition of Error displayed
4. Presumable cause
Note:
LED Green Red
Content
– –
Indoor
– –
Outdoor
5. Troubleshooting
Diagnosis
From 1/3
[Unit side]
YES
Does noise/vibration
occur when the cooling/
heating operation is
performed
normally?
NO
To 3/3

- -
Excessive noise/vibration (2/3)
Are the pipes
YES
contacting the
casing?
NO
Is it heard
YES
continuous hissing or
roaring sound?
NO
Are hissing sounds
YES
heard at the startup or
stopping?
NO
Is blowing sound
YES
heard at the start/stop
of defrosting during
heating?
NO
Is cracking noise
YES
heard during heating
operation?
NO
Hissing noise is
YES
heard during cooling
operation or after
stopping.
NO
-
'10 • PAC-SM-137$
Countermeasure
Rearrange the piping to
avoid contact with the
casing.
It is noise/vibration that
is generated when the
refrigerant gas or liquid
flow through inside of
piping of air-conditioner.
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
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
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
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
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.