Mitsubishi Heavy Industries FDT90VNPWVH Service Manual page 71

Error code
None
Remote control:
1. Applicable model
All models
2. Error detection method
3. Condition of Error displayed
4. Presumable cause
Note:
LED Green Red
– –
Indoor
5. Troubleshooting
Diagnosis
From previous page
[Unit side]
YES
Does noise/vibration
occur when the cooling/
heating operation is
performed
normally?
NO
To next page
70
-
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 defrost operation
during heating?
NO
Is cracking noise
heard during heating
operation?
NO
Hissing noise is
heard during cooling
operation or after
stopping.
NO
-
'19 • PAC-SM-334
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 defrost operation in the
heating mode. It is normal.
The noise/vibration occurs
when the refrigerant starts
YES
or stops flowing. It is
normal.
When the defrost operation
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
defrost operation, abrupt
YES
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
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.