Testing (Dual) Pressure Switch For Refrigerant - Komatsu PC200-8M0 Shop Manual

SEN06151-00

Testing (dual) pressure switch for refrigerant

k
Park the machine on a level surface, lower
the work equipment to the ground so that it is
stable, and stop the engine.
k
Turn the battery disconnect switch to the
"OFF" position and pull out the key.
a Note connector numbers and installed positions
when disconnecting wiring and hoses.
Testing
q If [879GKX] "Refrigerant Abnormality" is dis-
played by the self-diagnosis (on "03 Electrical
System" screen of "Abnormality Record" in the
machine monitor), test the dual pressure switch
connector P17.
To reset the self-diagnosis system (detection of
q
abnormality), the starting switch must be turned
OFF.
q The dual pressure switch is ON when the refrig-
erant pressure is normal, and OFF when it is ab-
normal.
a As the refrigerant pressure will drop when the
ambient temperature is below 0 °C, there is a
possibility that the dual pressure switch is
OFF. In such a case, the dual pressure
switch is actually normal (i.e., not defective).
1. Swing by 90 deg..
2. Remove the cab undercover.
3. Disconnect the dual pressure switch connector
P17.
36
80-100
Testing (dual) pressure switch for refrigerant
4. Ensure that the resistance between the
switch-side terminals from connector P17 is
shorted (ON). (If not shorted (OFF), the dual
pressure switch will detect a refrigerant pressure
abnormality.)
a When the dual pressure switch is OFF, con-
nect a pressure gauge to the high-pressure
side of the air conditioner compressor and
check the refrigerant pressure. See "Connec-
tion of service tool" and "Troubleshooting
with gauge pressure."
a If the refrigerant pressure is normal, the dual
pressure switch is defective.
(Dual) pressure switch
q
LA: 0.20 MPa {2 kg/cm
LB: 0.02 MPa {0.2 kg/cm
HA: 3.14 MPa {32 kg/cm
HB: 0.59 MPa {6 kg/cm
k
When replacing the dual pressure switch, re-
frigerant must be collected in advance.
a If resistance between the switch-side terminals
from connector P17 is shorted (ON), perform
"Troubleshooting for compressor and refrigerant
system".
PC200, 200LC, 220, 220LC-8M0
100 Air conditioner
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