Fujitsu ASU18RLF Service Instructions Manual page 53
Split type room air conditioner compact wall mounted / wall mounted / floor
compact cassette / slim duct inverter multi
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Also See for ASU18RLF:
- Service instructions manual (66 pages) ,
- Design & technical manual (51 pages) ,
- Service manual (21 pages)
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Trouble shooting 9
INDOOR UNIT Error Method:
Indoor Heat Ex. Thermistor Error
Detective Actuators:
Indoor unit controller PCB circuit
Heat exchanger thermistor
Forecast of Cause:
1. Connector failure connection 2. Thermistor failure
Test 1 : Check connection of Connector
Check if connector is loose or removed
Check erroneous connection
Check if thermistor cable is open
>>Reset Power when reinstalling due to removed connector or incorrect wiring.
OK
Test 2 : Remove connector and check Thermistor resistance value
Thermistor Characteristics (Rough value)
Temperature (°C)
Temperature (°F)
Resistance Value (k )
Temperature (°C)
Temperature (°F)
Resistance Value (k )
If Thermistor is either open or shorted, replace it and reset the power.
OK
Test 3 : Check voltage of Controller PCB (DC5.0V)
Make sure circuit diagram of each indoor unit and check terminal voltage at Thermistor (DC5.0V)
Compact wall mount circuit diagram (Connector connection)
BLACK
1
1
H/E Thermistor
BLACK
2
2
CN4
BLACK
3
3
Room Temp. Thermistor
BLACK
4
4
Wall mount circuit diagram (Direct soldering to PCB)
H/E Thermistor
RED
BLACK
1
1
1
CN3
2
2
2
WHITE
BLACK
3
3
BLACK
1
Room Temp. Thermistor
CN1
BLACK
2
Floor circuit diagram (Connector connection and Direct soldering to PCB)
GRAY
1
1
H/E (MID) Thermistor
CN3
GRAY
2
2
BLACK
1
Room Temp. Thermistor
CN1
BLACK
2
If the voltage does not appear, replace Controller PCB and execute the check operation again.
Indicate of Display:
Indoor Unit
Operation lamp : 4 time Flash
Timer lamp
ERROR CODE : [E : 42]
Detective details:
Heat exchanger thermistor is open or short is detected always.
-30
-20
-10
-22
-4
14
32
1131.91
579.59
312.27
176.03
60
65
140
149
11.64
9.69
Compact cassette circuit diagram (Connector connection)
1
CN5
2
1 1
CN8
2 2
Slim duct circuit diagram (Connector connection)
1
CN5
2
1
CN7
2
1 1
CN8
2 2
02-13
Outdoor Unit
A
: 2 time Flash
: Light ON
3. Controller PCB failure
0
10
20
30
50
68
86
103.34
62.91
39.57
GRAY
1
H/E (MID) Thermistor
GRAY
2
BLACK
Room Temp. Thermistor
BLACK
GRAY
1
H/E (MID) Thermistor
GRAY
2
BLACK
Room Temp. Thermistor
BLACK
Monitor
B
C
D
E
F
: Light OFF
n : n time blinking
40
50
104
122
25.64
17.06
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