Troubleshooting For Blower Motor System; Abnormal) - Komatsu PC88MR-10 Shop Manual

80 Appendix
A-3 Troubleshooting for blower motor system (No air
comes out or air flow is abnormal)
A-3 Troubleshooting for blower motor system (No air comes out or air
flow is abnormal)
No air comes out or air flow is abnormal due to blower motor system failure.
Failure
LCD of machine monitor on air conditioner operation screen lights up normally but air
Problem on
does not come out.
machine
Air flow does not match fan switch setting on air conditioner operation screen.
This failure is not checked with self-diagnosis function.
During cooling, if the air flow becomes abnormal after a certain time, the evaporator may
be frozen.
This may be due to the followings.
1. Defective compressor clutch relay (remains turned ON) (see Item 3-A of
"Troubleshooting for compressor and refrigerant system")
2. Evaporator temperature sensor mounting holder has come off (replace air conditioner
unit).
3. Improper adjustment of expansion valve (replace air conditioner unit)
When air comes out, fuses and motor are normal, and failure of wiring harness is unlikely.
For each connector and power transistor, see "Parts and connectors layout".
Related
information
When air comes out but air flow is abnormal during heating, the power transistor is
defective. In this case replace the air conditioner unit. (The power transistor may also be
defective when no air comes out.)
a The power transistor and the blower motor cannot be replaced.
Since T-adapter is not provided for the connector ACECU of the air conditioner controller
and the pin size is small, use the intermediate connector for troubleshooting (T-adapter is
also not provided for the intermediate connector, however, the pin size is larger).
When replacing the air conditioner wiring harness between connector ACECU of the air
conditioner controller and the intermediate connector, you must replace the entire air
conditioner unit.
No. Cause
Defective fuse No. 10 in
1
fuse box F01
Open circuit in wiring
harness
2
(wire breakage or
defective contact of
connector)
Ground fault in wiring
harness
3
(contact with ground
circuit)
Defective air conditioner
4
controller
Defective air conditioner
5
unit
80-72
(PC88MR-FK3-400-A-Z0-A)
Procedure, measuring location, criteria, and remarks
If fuse is blown, circuit probably has ground fault.
1. Turn starting switch to OFF position.
2. Disconnect connector AC02.
3. Remove fuse No. 10 in fuse box F01.
Resistance Between AC02 (female) (2) and F01-10
1. Turn starting switch to OFF position.
2. Disconnect connector AC02.
3. Remove fuse No. 10 in fuse box F01.
Resistance Between AC02 (female) (2) or F01-10 and ground
If no failures are found by the above checks, the air conditioner controller may
be defective. (Since this is an internal defect, troubleshooting cannot be
performed.)
If no failure is found by the above checks, the air conditioner unit may be
defective.
Max. 1 z
Max. 1 z
PC88MR-10