Komatsu PC200-8M0 Shop Manual page 1226

SEN06151-00
Indicated gauge
pressure
Air conditioner cycle is operating normally.
If there is any trouble (cooling trouble), there is another cause.
Pressure is normal
High-pressure: Approx. 1.5 to 1.7 MPa {15 to 17 kg/cm
Low-pressure: Approx. 0.13 - 0.2 MPa {1.3 - 2.0 kg/cm
Insufficient refrigerant
Clogging of receiver drier
<Both high-pres-
Clogging of expansion valve
sure and low-pres-
Gas leakage at thermoprobe of expan-
sure are too low>
sion valve
Low-pressure gauge
Defective evaporator temperature sensor
reads vacuum
or defective contact of sensor (coming off
of mounting clip)
Clogged or crushed piping
Filling too much with refrigerant
<Both high-pres- Defective cooling of condenser
sure and low-pres-
sure are too high>
Improper adjustment of expansion valve
(Valve is opened too wide)
Air in cycle parts
<High-pressure is
Clogged or crushed piping between com-
too high and low-
pressor and condenser
pressure is too low>
<High-pressure is
too low and Defective compressor (Compression
low-pressure is too trouble of compressor)
high>
*1: If refrigerant leaks, compressor oil in the air conditioner circuit always leaks, too. So perform the check
mainly on pipe joints and dirty parts with oil.
*2:
k
When replacing a cooling cycle part, see "Caution about refrigerant" and collect refrigerant. After
replacing it, fill up the air conditioner system with refrigerant again.
*3: Sight glass is on the air conditioner hose near condenser.
68
80-100
Cause
Bubble can be seen through sight glass. *1,
*3
There is a temperature difference between
inlet and outlet pipes of receiver drier.
Tank is frosty
Expansion valve is frosted
Low-pressure gauge reads vacuum
Evaporator is frozen
Flow rate of refrigerant is reduced due to
freezing.
(At Cool Max. and HI speed of fan, later it
becomes not to cold.)
Piping between receiver drier and com-
pressor is clogged or crushed.
If clogged completely, low-pressure gauge
reads vacuum
Connect gauge manifold
Dirty condenser, clogging or crushing of
fins, or defective rotation of cooling fan
Bubble can be seen through sight glass. *3
Bubble can be seen through sight glass. *3
There is a remarkable temperature differ-
ence across clogged part
Both high-pressure and low-pressure are
balanced while compressor is in operation.
Compressor has seized and is extremely
hot.
Troubleshooting with gauge pressure
Check method
2
}
2
}
PC200, 200LC, 220, 220LC-8M0
100 Air conditioner
Remedy
–
Collect refrigerant, then
fill up with proper quan-
tity of refrigerant again
*2
Replace
*2
Clean or replace
*2
Replace
*2
Repair or replace
Replace receiver drier
Collect refrigerant, then
fill up with proper quan-
tity of refrigerant again
*2
Clean or replace
*2
Collect refrigerant, then
fill up with proper quan-
tity of refrigerant again
*2
Clean, repair fins, or
repair or replace con-
denser
*2
Replace
*2
Evacuate and then fill up
with proper quantity of
refrigerant again
*2
Clean inside of cycle or
replace
*2
Replace
*2