Komatsu Galeo PC138US-8 Shop Manual page 693

SEN02467-00
Trouble (3) Air does not come out (Air flow is insufficient).
Related
information
Defective blower relay (Inter-
1
nal disconnection)
Defective power transistor
2
(Internal defect)
Defective blower motor
Possible causes
3
(Internal defect)
and standard
value in normal
state
Disconnection in wiring har-
ness (Disconnection in wiring
4
or defective contact in con-
nector)
40
Cause Standard value in normal state/Remarks on troubleshooting
a Prepare with starting switch OFF, then carry out troubleshoot-
a Prepare with starting switch OFF, then turn starting switch ON
chassis ground
a Prepare with starting switch OFF, then turn starting switch ON
Operate between Low and
a Prepare with starting switch OFF, then turn starting switch ON
M
Between (1) – (2)
If above voltage is normal and blower motor does not revolve,
blower motor is defective.
a Prepare with starting switch OFF, then carry out troubleshoot-
Wiring harness between F01-10 – fuse in
unit – R20 (female) (1)
Wiring harness between R20 (female) (3) –
AC
W
Wiring harness between F01-11 – R20
(female) (4)
Wiring harness between R20 (female) (2) –
M (wiring side) (1)
B
Wiring harness between M
– P
TR
Wiring harness between P
(1) – chassis ground (T14)
Wiring harness between P
(2) – AC
Wiring harness between P
(4) – AC
ing without turning starting switch ON (coil side).
R20 (male)
Between (1) – (3)
and carry out troubleshooting (contact side).
R20 Air conditioner switch
Between (4) –
Air blow position
and carry out troubleshooting.
Fan switch
Medium and High.
and carry out troubleshooting.
(wiring side) Air conditioner switch
B
Air blow position
ing without turning starting switch ON.
(wiring side) (36)
(wiring side) (2)
B
(wiring side) (3)
TR
TR
(wiring side) (8)
W
TR
(wiring side) (7)
W
40 Troubleshooting
Resistance
140 – 340 z
Voltage
20 – 30 V
If air flow changes according to
operation of fan switch, power
transistor is normal.
Voltage
20 – 30 V
Resis-
tance
Resis-
tance
Resis-
tance
Resis-
tance
Resis-
tance
(wiring side) Resis-
tance
(wiring side) Resis-
tance
(wiring side) Resis-
tance
PC138US, USLC-8
Max. 1 z
Max. 1 z
Max. 1 z
Max. 1 z
Max. 1 z
Max. 1 z
Max. 1 z
Max. 1 z