Komatsu PC200-8M0 Shop Manual page 1198

SEN06151-00
Troubleshooting chart 2
1. During cooling, the blower fan motor does not operate or the rotation speed does not match the air flow
setting.
Probable cause
Wire breakage or defective con-
nection
Defective blower fan motor
Defective power transistor (PTR) Operate the fan switches in order and check the fan speed.
2. During cooling, the blower fan motor is normal but the flow of air is very light.
Probable cause
Large duct resistance
Air leakage through duct joints
Obstruction at evaporator inlet
Defective evaporator tempera-
ture sensor, defective contact of
evaporator temperature sensor,
defective expansion valve*
*: The evaporator temperature sensor and expansion valve are located inside the air conditioner unit.
3. Pressure abnormality (high-pressure/low-pressure) during cooling.
Probable cause
Insufficient refrigerant
Overcharge with refrigerant
Judgment by pressure at
inlet/outlet of compressor
40
80-100
Check method
Check the connector for disconnection.
See "Parts and connectors layout".
Operate the fan switches in order and check the fan speed. See
"Air conditioner unit".
Check method
Check the filter for clogging and the duct for crushing.
Check duct joints.
See "Testing air leakage (duct)".
Check evaporator for stain and obstruction
Evaporator is frozen.
Sensor fixing clip inspection, sensor contaminated
Inspect the air conditioner hose around the dual pressure
switch for frost.
(when freezing has advanced even further)
Check method
Check the refrigerant volume through sight glass.
Specifically, perform checking with the gauge manifold con-
nected.
Normal pressure range
Low-pressure: Approx. 0.13 - 0.2 MPa {1.3 - 2.0 kg/cm
High pressure: Approx. 1.5 - 1.7 MPa {15 – 17 kg/cm
Temperature in operator's cab: 30 to 35 °C, Engine speed:
Approx. 1,500 rpm
100 Air conditioner
Troubleshooting chart 2
Remedy
Repair broken parts
and connect cor-
rectly
Replace
Replace
Remedy
Repair
Repair
Remove obstruc-
tion and clean
Repair or replace
Remedy
Repair leaking part,
then charge with
proper quantity of
refrigerant again
Collect refrigerant,
then fill up with
proper quantity of
refrigerant again
2
} See Troubleshoot-
2 ing with gauge pres-
}
sure
PC200, 200LC, 220, 220LC-8M0