Komatsu PC88MR-10 Shop Manual page 1374

80 Appendix
Troubleshooting chart 2
4. During cooling, the compressor will not operate smoothly, or at all.
a See "Troubleshooting of compressor system (Air is not cooled)".
Troubled
Probable cause
part
Compressor
Slack of belt
belt
Trouble in compressor
Insufficient compressor oil
Compressor
Seizing on compressor
Drop of battery voltage
Open or short circuit in coil
Magnet
clutch
Wire breakage or defective
connection of ground wire
Defective compressor clutch
Relay
relay
Refrigerant Low/high pressure (Operation
pressure of pressure switch)
Pressure
Defective pressure switch
switch
5. During heating, blower fan motor is normal but air flow alone is insufficient.
Probable cause
Large duct resistance
Air leakage through duct
joints
Clogging of heater core fins Check heater core fins for clogging
6. Engine coolant temperature or volume abnormalities during heating or cooling
Probable cause
Low engine coolant
temperature
Low engine coolant level
Insufficient circulation of
engine coolant
The connection of IN and
OUT heater hoses is in
reverse.
7. Fan speed abnormalities during cooling
Probable cause
Fan speed is low
80-50
Deflection of belt is large.
See "Checking and adjusting air
conditioner compressor belt tension" in
the "Testing and adjusting" in Chapter
30.
Slip of belt
Heating of compressor
Slip of clutch
Inspect with multimeter (10 to 20 z)
Check ground cable and joints.
See "Troubleshooting for compressor
and refrigerant system".
See "Testing relays"
See "Troubleshooting with gauge
pressure".
See "Troubleshooting for compressor
and refrigerant system".
See "Testing refrigerant (dual) pressure
switch".
Check method
Check the filter for clogging and the duct for crushing.
Check the duct joints by referring to "Testing air leakage
(duct)."
Check method
Warm up engine, and then check engine coolant
temperature
Check coolant level in radiator
Check engine coolant piping for clogging.
(Hose, pipe and core)
Check the destination of heater hoses
Check method
See "Replacing fan belt" in "Testing and adjusting" in
Chapter 30.
Check method
Remedy
Adjust tension
Repair or replace
See "Handling
compressor oil".
Charge battery
Replace
Repair
Replace
See
"Troubleshooting
with gauge
pressure".
Replace
Remedy
Repair
Repair
Clean
Remedy
Find out cause
Add coolant
Bleed air and correct
Correct
Remedy
Replace
PC88MR-10