SiAF332111E Symptom-based Troubleshooting
Part 6 Service Diagnosis 179
2. Symptom-based Troubleshooting
Symptom Supposed Cause Countermeasure
1 The system does not start operation at all. Blowout of fuse(s) Turn Off the power supply and then
replace the fuse(s).
Cutout of breaker(s) • If the knob of any breaker is in its
OFF position, turn ON the power
supply.
• If the knob of any circuit breaker is
in its tripped position, do not turn
ON the power supply.
Power failure After the power failure is reset,
restart the system.
The connector loose or not fully
plugged in
Turn off the power supply to verify
the connection of the connector.
2 The system starts operation but makes an
immediate stop.
Blocked air inlet or outlet of indoor
or outdoor unit
Remove obstacle(s).
Clogged air filter(s) Clean the air filter(s).
3 The system does not cool air well. Blocked air inlet or outlet of indoor
or outdoor unit
Remove obstacle(s).
Clogged air filter(s) Clean the air filter(s).
Enclosed outdoor unit(s) Remove the enclosure.
Improper set temperature Set the temperature to a proper
degree.
Airflow rate set to LOW Set it to a proper airflow rate.
Improper direction of air diffusion Set it to a proper direction.
Open window(s) or door(s) Shut it tightly.
Cooling operation
Direct sunlight received
Hang curtains or shades on
windows.
Cooling operation
Too many people staying in a room
The model must be selected to
match the air conditioning load.
Cooling operation
Too many heat sources (e.g. OA
equipment) located in a room
Dry operation
The reason is that the dry operation
serves not to reduce the room
temperature where possible.
Change the system to cooling
operation.
4 The system does
not operate.
The system stops and
immediately restarts
operation.
If the operation lamp on the remote
controller turns ON, the system will
be normal. These symptoms
indicate that the system is
controlled so as not to put
unreasonable loads on the system.
Normal operation. The system will
automatically start operation after a
lapse of five minutes.
Pressing the temperature
setting button immediately
resets the system.
The system stops immediately
after turning ON the power
supply.
The system is in preparation mode
of microcomputer operation.
Wait for a period of approximately
one minute.
5 The system
makes
intermittent
stops.
The remote controller displays
error codes U4 or U5, and the
system stops but restarts after
a lapse of several minutes.
The system stops due to an
interruption in communication
between units caused by electrical
noises coming from equipment
other than air conditioners.
Remove causes of electrical noises.
If these causes are removed, the
system will automatically restart
operation.
6 The system
conducts fan
operation but not
cooling
operation.
This symptom occurs
immediately after turning ON
the power supply.
The system is in preparation mode
of operation.
Wait for a period of approximately
10 minutes.
The remote controller displays
the mark for centralized
control; no cooling operation is
performed. Switch to fan
operation.
In thermal storage operation, the
unit is set to fan operation in cooling
operation, and the remote controller
shows the mark for centralized
control.
Normal operation.
ON
Knob
Tripped
OFF
Circuit breaker
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