Sharp AU-A18 (serv.man8) Service Manual ▷ View online
AH-AP18CS
AH-AP24CS
AU-A18CS
AU-A24CS
AH-AP24CS
AU-A18CS
AU-A24CS
16
TROUBLESHOOTING GUIDE OF CONTROL CIRCUIT
measure the secondary voltage
of transformer.
of transformer.
YES
NO
YES
NO
The machine does not function
at all with remote controller and
switches on the indoor unit.
at all with remote controller and
switches on the indoor unit.
Using a tester, measure the
voltage between anodes of D1
and D2 on PWB ass'y.
voltage between anodes of D1
and D2 on PWB ass'y.
Is the measured value
approx. 17.0 Vac ?
Replace the PWB with a new
one.
one.
Is the WPE1 fuse down ?
Replace the fuse and varistor
with new ones.
with new ones.
Replace the transformer with
a new one.
a new one.
17
AH-AP18CS
AH-AP24CS
AU-A18CS
AU-A24CS
AH-AP24CS
AU-A18CS
AU-A24CS
YES
NO
NO
YES
The machine does not function
with remote controller
with remote controller
Push button "OI" on the wireless
remote controller.
remote controller.
Is transmitting
indicator of the remote
controller active ?
Is indicator lamp of
indoor unit proper ?
Replace the
PWB with a
new one.
PWB with a
new one.
Does beep sound
from the indoor unit ?
Using a tester,
measure the voltage
between terminals
of resistor R26
on the PWB ass'y.
measure the voltage
between terminals
of resistor R26
on the PWB ass'y.
Push the button "OI".
Are batteries of the
wireless remote controller
proper ?
Replace the batteries
with new ones.
with new ones.
Replace the wireless
remote controller.
remote controller.
When the signal is
received, does the voltage
change ?
Replace the PWB with a new
one.
one.
PWB is normal.
Inspect the outdoor unit.
Inspect the outdoor unit.
NO
YES
NO
YES
Replace the photo
detector unit with a new
one.
detector unit with a new
one.
NO
YES
AH-AP18CS
AH-AP24CS
AU-A18CS
AU-A24CS
AH-AP24CS
AU-A18CS
AU-A24CS
18
The room is not cooled at all
or not cooled.
The compressor does not operate.
or not cooled.
The compressor does not operate.
Measure resistances of TH1 and TH2.
Push the button "AUX." on
the indoor unit, for more than 5 sec.
the indoor unit, for more than 5 sec.
Is the voltage
between terminal "N" and
"1" of the terminal board the
power supply voltage ?
Are the resistances
conformed Fig. 1 ?
Replace the thermistor ass'y
with a new one.
with a new one.
NO
YES
YES
NO
Replace the PWB ass'y with a new one.
Fig. 1
Using a tester, measure voltage at
the terminals on the terminal board.
the terminals on the terminal board.
100
80
60
40
20
0
-10
0
10
20
30
40
Resistance
Thermistor
Room temperature
Heat exchange
Color
Yellow
Orange
To measure the resistance, first remove
the connector as shown at right.
the connector as shown at right.
Room temperature
thermistor TH1
Tester
Connector
No. 3 to 4
No. 1 to 2
Fig. 1 Temperature properties of indoor thermistors
K
Heat exchange thermistor
TH2 (orange)
25
TH2 (orange)
25
°C resistance 15 K
Room temperature
thermistor TH1 (yellow)
25
thermistor TH1 (yellow)
25
°C resistance 10 K
Heat exchange
thermistor TH2
Tester
4
1
CN4
The control circuit is normal.
The compressor may be defective.
The running capacitor may be
defective.
Refrigerant may be leaked.
The outdoor fan motor may be
defective.
The outdoor fan motor capacitor
may be defective.
The compressor may be defective.
The running capacitor may be
defective.
Refrigerant may be leaked.
The outdoor fan motor may be
defective.
The outdoor fan motor capacitor
may be defective.
19
AH-AP18CS
AH-AP24CS
AU-A18CS
AU-A24CS
AH-AP24CS
AU-A18CS
AU-A24CS
For AH-AP24CS / AU-A24CS
The room is not cooled at all
or not cooled.
The compressor does not operate.
or not cooled.
The compressor does not operate.
Measure resistances of TH1 and TH2.
The control circuit is normal.
The compressor may be defective.
The running capacitor may be
defective.
Refrigerant may be leaked.
The outdoor fan motor may be
defective.
The outdoor fan motor capacitor
may be defective.
The compressor may be defective.
The running capacitor may be
defective.
Refrigerant may be leaked.
The outdoor fan motor may be
defective.
The outdoor fan motor capacitor
may be defective.
Push the button " AUX." on
the indoor unit, for more than 5 sec.
the indoor unit, for more than 5 sec.
Is the voltage
between terminal of black
lead wire on the relay in the outdoor unit
and terminal "N" on the terminal board the
power suuply voltage ?
Are the resistances
conformed Fig. 1 ?
Replace the thermistor
ass'y with a new one.
ass'y with a new one.
NO
YES
YES
NO
Replace the PWB ass'y with a new one.
Using a tester, measure voltage at
the terminals on the terminal board.
the terminals on the terminal board.
Replace the relay in the outdoor unit with
a new one.
a new one.
Is the voltage
between terminal " N " and
" 2 " in the outdoor unit
the power supply
voltage ?
YES
NO
Display