Symptom-Based Troubleshooting - Daikin ALTHERMA HT Service Manual

ESIE09-08B

1. Symptom-based Troubleshooting

Symptom
1 The system does not start operation at all.
2 The system starts operation but makes an
immediate stop.
3 The unit is turned on but the unit is not heating as
expected.
4 The system does The system stops and
not operate. immediately restarts operation.
The remote control displays
"UNDER CENTRALIZED
CONTROL", which blinks for a
period of several seconds
when the OPERATION button
is depressed.
The system stops immediately
after turning ON the power
supply.
5 The system The remote control displays
makes malfunction codes "U4" and
intermittent "U5", and the system stops but
stops. restarts after a lapse of several
minutes.
Troubleshooting
Supposed Cause
Blowout of fuse(s)
Cutout of breaker(s)
Power failure
Open phase in power supply
cable
Blocked air inlet or outlet of
outdoor unit
The temperature setting is not
correct.
Capacity shortage.
The water volume in the
installation is too low.
The water flow is too low.
If the OPERATION lamp on the
remote control 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.
The system is controlled with
centralized control.
The system is in preparation
mode of micro computer
operation.
The system stops due to an
interruption in communication
between units caused by
electrical noises coming from
equipment other than air
conditioners.

Symptom-based Troubleshooting

Countermeasure
Turn Off the power supply and
then replace the fuse(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.
ON
Knob
Tripped
OFF
Circuit breaker
After the power failure is reset,
restart the system.
Check power supply. After that,
properly connect the power
supply cable, and then turn ON
the power supply.
Remove obstacle(s).
Check the controller set point +
settings (room + water).
Check if the cooling fans at the
rear of the switch box are working
properly.
Make sure that the water volume
in the installation is above the
minimum required value.
Check if there is no bypass of the
water circuit.
• Check that all shut-off valves of
the water circuit are completely
open.
• Check if the water filter needs
cleaning.
• Make sure there is no air in the
system (purge air).
• Make sure that the expansion
vessel is not broken.
• Check the water pressure on
the manometer > 0,3 bar.
Normal operation. The system will
automatically start operation after
a lapse of five minutes.
Recovery/vacuum mode is active
(higher priority mode).
Wait for a period of approximately
one minute.
Remove causes of electrical
noises.
If these causes are removed, the
system will automatically restart
operation.
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