Komatsu PC88MR-10 Shop Manual page 1394

80 Appendix
A-2 Troubleshooting for compressor and refrigerant
system (Air is not cooled)
No. Cause
Open circuit in wiring
4
harness
Ground fault in wiring
harness
5
(contact with ground
circuit)
Short circuit in wiring
6
harness
Defective air conditioner
7
controller
Defective machine
monitor
8
(defective switch)
Defective air conditioner
9
unit
80-70
Procedure, measuring location, criteria, and remarks
1. Turn starting switch to OFF position.
2. Disconnect connector R21.
a Make sure that result of check of cause 2 is normal (air conditioner
compressor is normal).
Between connector R21 (female) (5) and F01-10
(Pressure switch is turned ON)
Between connector R21 (female) (3) and chassis
ground
Resistance
(Air conditioner compressor coil resistance)
Between F01-14 and AC01 (female) (7)
a Relay coil resistance
a If the fuse is not blown, skip troubleshooting.
1. Turn starting switch to OFF position.
2. Disconnect connectors AC03 and R21, and connect a T-adapter to the
female side of AC03.
Resistance Between AC03 (female) (1) and chassis ground
1. Turn starting switch to OFF position.
2. Disconnect connectors AC01, AC02, and R21.
a Ensure that test result for cause 2 is normal.
Between wiring harness side (2) of connector R21
Resistance
and AC02 (female) (2), (3), and (4)
1. Turn starting switch to OFF position.
2. Disconnect connector R21.
3. Turn starting switch to ON position.
4. Display the air conditioner operation screen on the machine monitor and
press the A/C switch.
Voltage Between connector R21 (female) (2) and ground
1. Turn starting switch to ON position.
2. Display the air conditioner operation screen on the machine monitor.
Press A/C switch.
If no failure is found by the above checks, the air conditioner unit may be
defective.
Max. 1 z
Approx. 15
z
300 to 500
z
Min. 1 Mz
Min. 1 Mz
Max. 1 V
"A/C ON" is displayed
PC88MR-10