Troubleshooting For Compressor And Refrigerant System (Air Is Not Cooled) - Komatsu PC200-8M0 Shop Manual

SEN06151-00
Troubleshooting for compressor and refrigerant system (Air is not
cooled)
Failure Air is not cooled due to compressor or refrigerant system failure.
q
When engine is started and A/C switch is pressed on air conditioner screen of machine monitor, air is
Problem on
not cooled as displayed on screen.
machine
q
Air conditioner compressor does not operate.
q
Referring to "Testing with self-diagnosis function", display "Electrical Systems" screen on the machine
monitor and check to see if the refrigerant pressure is abnormal by checking whether failure code
[879GKX] is displayed. If the refrigerant pressure is abnormal, the compressor will not be turned ON
and air will not subsequently not be cooled.
a Abnormal refrigerant pressure indicates that "Signal ((21) of connector ACECU) from the dual pres-
sure switch is not grounded".
q
In certain cases, the air conditioner will not turn on at 3 °C or lower (normal).
Related infor-
q If no air comes out, see "Troubleshooting for blower motor system".
mation
q
For each connector and fuse, see "Parts and connectors layout".
a A T-adapter is provided only for the connector AC03.
q
Since connector ACECU of the air conditioner controller has small pins and does not have a T-adapt-
er, 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 inter-
mediate controller, the air conditioner unit must be replaced.
Cause
Defective dual pressure
1
switch system
Defective air conditioner
2
compressor
Defective compressor
3 clutch relay (does not turn
ON)
60
80-100

Troubleshooting for compressor and refrigerant system (Air is not cooled)

Procedure, measuring location, criteria and remarks
a Perform this check when failure code [879GKX] is displayed on "Electrical Sys-
tems" screen of machine monitor.
See failure code [879GKX].
a In certain cases, the dual pressure switch may be operating normally and set to
OFF, therefore, if abnormality is indicated (i.e., switch OFF), attach a pressure
gauge to the air conditioner compressor and check the refrigerant pressure. (See
"Troubleshooting with gauge pressure.")
k
Before replacing pressure switch, collect refrigerant.
1. Turn starting switch to OFF position.
2. Disconnect the connector AC03 from the air conditioner compressor and connect a
T-adapter to the male side.
a Ensure connection of air conditioner compressor ground cable (E).
(See "Parts and connectors layout".)
Between connector AC03 (male) (1) and the chassis
Resistance
ground (i.e., air conditioner compressor coil resistance)
q
Referring to "Testing relays", check sound when compressor clutch relay is turned
ON.
Click is heard -----------------------------------------A
a When A above is abnormal and B below is abnormal and C is normal (if the relay is
normal), go to cause 4.
1. Turn starting switch to OFF position.
2. Disconnect connector R21.
3. Use a wire to short-circuit (3) (white) and (5) (red on yellow) of connector R21
(wiring harness side) . (This forces the compressor to operate without using the
relay.)
4. Turn starting switch to ON position.
Air is cooled -----------------------------------------B
1. Turn starting switch to OFF position.
2. Disconnect connector R21 and troubleshoot in that condition.
Between (1) and (2) of connector R21
Resistance
(male) (i.e., coil resistance)
100 Air conditioner
Approx. 15 z
C
PC200, 200LC, 220, 220LC-8M0
300 –
500 z