Troubleshooting For Blower Motor System (No Air Comes Out Or Air Flow Is Abnormal) - Komatsu PC200-8M0 Shop Manual

100 Air conditioner

Troubleshooting for blower motor system (No air comes out or air flow is abnormal)

Troubleshooting for blower motor system (No air comes out or air flow
is abnormal)
Failure No air comes out or air flow is abnormal due to blower motor system failure.
q
LCD of machine monitor on air conditioner operation screen lights up normally but air does not come
Problem on
out.
machine
q
Air flow does not match fan switch setting on air conditioner operation screen.
q
This failure is not checked with self-diagnosis function.
q
In cases where the blown-air volume begins to behave in an unpredictable manner after a certain
while during cooling, freezing of the evaporator is a likely cause.
This may be due to the followings.
1) Defective compressor clutch relay (i.e., stuck in ON position) (see item 3-A from "Trouble-
shooting for compressor and refrigerant system")
2) Detachment of the evaporator temperature sensor's mounting holder (Replace the air condi-
tioner unit)
3) Incorrect adjustment of expansion valve (Replace air conditioner unit)
Related infor- q If air comes out, fuse and motor are normal, and also wiring harness is normal.
q
mation For each connector and power transistor, see "Parts and connectors layout".
a The power transistor is on the rear side of the air conditioner unit.
q
If air comes out but its flow is abnormal in heating mode, replace power transistor. (When no air
comes out, the power transistor may also be defective.)
a The blower motor cannot be replaced unless the air conditioner unit is removed once.
q
Since connector ACECU of the air conditioner controller has small pins and does not have a
T-adapter, perform troubleshooting by using the intermediate connector (Although the intermediate
connector does not have a T-adapter either, it does have large pins).
q
To replace the air conditioner harness between air conditioner controller connector ACECU and in-
termediate controller, the air conditioner unit must be replaced.
Cause
Defective fuse No. 11 in
1
fuse box F01
2 Defective power transistor
Open circuit in wiring har-
ness
3
(wire breakage or defective
contact of connector)
Ground fault in wiring har-
4 ness
(contact with ground circuit)
Defective air conditioner
5
controller
Defective air conditioner
6
unit
PC200, 200LC, 220, 220LC-8M0
Procedure, measuring location, criteria and remarks
If fuse is blown, circuit probably has ground fault.
1. Turn starting switch to OFF position.
2. Replace power transistor.
a If air comes out and air flow can be adjusted, the original power transistor is de-
fective.
1. Turn starting switch to OFF position.
2. Disconnect connector AC02.
3. Remove fuse No. 11 of fuse box F01.
Resistance Between AC02 (female) (2) and F01-11
1. Turn starting switch to OFF position.
2. Disconnect connectors AC02 and R21.
3. Remove fuse No. 11 of F01.
Resistance Between AC02 (female) (2) or F01-11 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 above checks, air conditioner unit may be defective.
SEN06151-00
Max. 1 z
Max. 1 z
63
80-100