Troubleshooting Chart - Toshiba RAS-18YKH-E Service Manual

Troubleshooting Procedures :
• Following details of "What to be pre-checked
first", make sure of the basic items.
• When there is no trouble corresponding to
above, check in detail the faulty parts follow-
ing "How to judge faulty parts by symptoms"
later.
9-1. What to be Prechecked First
9-1-1. Power Supply Voltage
The line voltage must be AC 220–240V (RAS-
18YKH-E, RAS-18YAH-E), 240V (RAS-18YKH-A,
RAS-18YAH-A). If the line voltage is not within this
range, this air conditioner may not work normally.
No. Operation of air-conditioner
1 When the breaker is turned on, the
OPERATION lamp on the setting
indication part flashes.
2 Fan speed remains unchanged in the
dry mode.
3 Room temperature is in the range
under which the compressor is turned
off, but the compressor will not stop.
4 The compressor will not switch on or
off even when the thermo control is
operated in the dry operation.
5 The PRE-DEF. lamp comes on when
the heating operation is started.
6 The outdoor fan stops once in the
while during the heating operation.
7 Compressor does not work though
room temperature is in the range of
turning the compressor on.
8 During automatic operation, the
operation mode changes.
9 During automatic operation mode, the
fan only operation continues.

9. TROUBLESHOOTING CHART

Table 9-1-1
The OPERATION lamp flashes, indicating that power is
turned on. If this happens, push the START/STOP button
once to cause the lamp to stop flashing. A power outage
also causes the lamp to flash.
Fan speed is automatically controlled in the dry mode.
The compressor will not stop while the compressor on hold
timer (3-minutes timer) is actuated.
In the dry mode, the compressor goes on and off at regular
intervals, independent of the thermo control.
The PRE-DEF. lamp comes on during defrost operation and
when the indoor heat exchanger temperature is low when the
heating operation is started. At this time, the indoor fan is
stopped to prevent cold air from drifting into the room.
• When the indoor heat exchanger temperature is high, the
outdoor fan may be stopped by the high-temperature limit
control operation.
Compressor does not work while the compressor restart
delay (3-min.) timer is active. The same is true after power is
turned on, as the time is still active.
After selection of the cooling and heating operation, the
operation mode is selected again when the compressor off
mode continues for 15 min. according to the room tempera-
ture.
When the room temperature is within setting temperature ±
1°C the fan only mode is selected.
– 20 –
9-1-2. Incorrect Cable Connection between
Indoor and Outdoor Units
The indoor unit is connected to the outdoor unit with
4 cables. Make certain that the indoor and outdoor
units have been connected properly, with terminals
assigned the same numbers wired to each other.
If the connectors are not connected as specified, the
outdoor unit will not operate normally, or OPERA-
TION lamp and TIMER lamp will flash (5Hz).
9-1-3. Misleading but Good Operations
(Program Controlled Operation)
The microcomputer performs the operations listed in
Table 9-1-1 to control the air conditioner. If a claim
is made on the operation, check whether it corre-
sponds to the contents in the Table 9-1-1.
If it does, it is an indispensable operation for the
control and maintenance of the air conditioner: it is
not a failure of the unit.
Description