Operates But Does Not Heat - Mitsubishi Heavy Industries KXZ Series Service Manual

Error code
None
Remote control:
7-segment display: –
1. Applicable model
All models
2. Error detection method
3. Condition of error displayed
4. Presumable cause
• 4-way valve anomaly
• Poor compression of
compressor
• Expansion valve anomaly
operation
Note:
LED Green Red
Keeps flashing Stays OFF
Indoor
Keeps flashing Stays OFF
Outdoor
5. Troubleshooting
Diagnosis
Check the indoor fan operation.
Check the temperature difference between
return and suction air of indoor unit.
Is the
temperature difference
between return and
suction air 10-30° at
heating?
NO
Is the compressor
operating?
YES
Is the
compressor rotation
speed low?
YES
Check following operation control function.
. Control for determine compressor rotation speed
. Protective control by controlling compressor
rotation speed
Which control is appropriate to this phenomenon.
Is the
operating conditions of
indoor/outdoor unit
under rated condition?
NO
The unit is operating normally, but is operating
under the protective control of compressor or
other respective components.
63
–
Content

Operates but does not heat

Does the
YES heat load increase after
installation?
YES
Mistake in model selection.
Calculate heat load once more.
NO
" WAIT "
message is displayed [for
3 seconds] when performing
YES
cooling, dehumidifying or heating
operation from remote
control?
NO
YES
Note (1) Outdoor: 7ºC
Indoor : 20ºCDB
–
'14 • KX-SM-221
Countermeasure
It is normal.
(This unit is designed
to start in the soft start
mode by detecting the
NO
compressor under-dome
temperature when it restart
after power reset.)
It is necessary to replace to
higher capacity unit or to
install additional unit.
Compressor refrigerant
oil protective control at
starting is activated.
For the contents of control,
refer to the compressor
start control.
Compressor may be
NO
stopped by the error
detection control.
For the contents of control,
refer to anomalous stop
control by controlling
compressor rotation speed
of microcomputer control
function.
Check the followings.
• Minor clogging of filter
• Minor fouling of heat exchanger
• Minor short-circuit of airflow
• Slightly insufficient or excessive
refrigerant amount
• Poor compression of compressor
Check suspicious points
considering appropriate
operation control.
Check the followings for
reference.
• Severe clogging of filter
• Severe clogging of heat
exchanger
• Severe short-circuit of airflow
• Severely insufficient or
excessive refrigerant amount
• Under protective control of
compressor
• Indoor unit fan tap setting
• Valid setting of silent mode