Komatsu 830E-AC Shop Manual page 954

COMPONENT REPLACEMENT
Hoses and Fittings
When replacing hoses, be sure to use the same type
and ID hose you removed. When hoses or fittings are
shielded or clamped to prevent vibration damage, be
sure these are in position or secured.
Lines
Always use two wrenches when disconnecting or
connecting A/C fittings attached to metal lines. Cop-
per and aluminum tubing can kink or break very eas-
ily. When grommets or clamps are used to prevent
line vibration, be certain these are in place and
secure.
It is important to always tighten the fittings to the
proper torque. Failure to do this may result in
improper contact between mating parts and leak-
age may occur. Refer to the following torque
chart for tightening specifications.
Fitting Size Foot Pounds
6 10 - 15 ft.lbs.
8 24 - 29 ft.lbs.
10 26 - 31 ft.lbs.
12 30 - 35 ft.lbs.
Installation torque for the single M10 or 3/8 in. cap
screws securing the inlet and outlet fittings onto the
compressor ports is 15-34 N·m (11-25 ft lbs).
Expansion Valve
When removing the expansion valve from the sys-
tem, remove the insulation, clean the area and dis-
connect the line from the receiver-drier. Detach the
capillary (bulb) and external equalizer tube (if
present) from their mounting locations. Remove the
expansion valve from the evaporator inlet. Expansion
valve service is limited to cleaning or replacing the fil-
ter screen. If this is not the problem, replace the
valve. Secure the capillary and equalizer, if used, to
clean surfaces and replace or attach any insulating
material.
N4-28
Receiver-Drier
The receiver-drier can not be serviced or repaired. It
must be replaced whenever the system is opened
for any service. The receiver-drier has a pressure
switch to control the clutch, and should be removed
and installed onto the new unit.
NOTE: Do not use PAG oil to lubricate O-rings or fit-
tings. PAG oil will attract moisture and will corrode fit-
tings when used externally. Use only clean mineral
oil to lubricate fittings and O-rings during assembly.
Thermostat
A thermostat can be stuck open or closed due to con-
tact point wear or fusion. The thermostat temperature
sensing element (capillary tube) may be broken or
kinked closed and therefore unable to sense evapo-
rator temperature.
When thermostat contact points are stuck open or
the sensing element can not sense temperature in
the evaporator, the clutch will not engage (no A/C
system operation). Causes are a loss of charge in
the capillary tube or a kink, burned thermostat con-
tact or just no contact. When troubleshooting, bypass
the thermostat by hot wiring the clutch coil with a
Newton Meters
fused lead. If the clutch engages, replace the thermo-
stat.
14 - 20 Nm
Thermostat contact points may be fused (burned)
33 - 39 Nm
closed and the clutch will not disengage. Causes are
a faulty switch that could be due to fatigue. The ther-
36 - 42 Nm
mostat must be replaced. When the clutch will not
41 - 47 Nm
disengage you may also note that condensate has
frozen on the evaporator fins and blocked air flow.
There will also be below normal pressure on the low
side of the system. Side effects can be compressor
damage caused by oil accumulation (refrigeration oil
tends to accumulate at the coldest spot inside the
system) and lower than normal suction pressure that
can starve the compressor of oil.
Operator Comfort 10/06 N04031