Komatsu 830E-AC Shop Manual page 964

Preliminary Checks
If the system indicates insufficient cooling, or no cool-
ing, the following points should be checked before
proceeding with the system diagnosis procedures.
NOTE: If the truck being serviced is a model 830E-
AC or a 930E, be certain the rest switch in the cab is
ON. Place the GF cutout switch in the CUTOUT
position.
Some simple, but effective checks can be performed
to help determine the cause of poor system perfor-
mance. Check the following to ensure proper system
operation.
• Compressor belt - Must be tight, and aligned.
• Compressor clutch - The clutch must engage. If it
does not, check fuses, wiring, and switches.
• Oil leaks - Inspect all connection or components
for refrigeration oil leaks (especially in the area of
the compressor shaft). A leak indicates a
refrigerant leak.
• Electrical check -
connections for possible open circuits or shorts.
Check all system fuses.
• Cooling system - Check for correct cooling
system operation. Inspect the radiator hoses,
heater hoses, clamps, belts, water pump,
thermostat and radiator for condition or proper
operation.
• Radiator shutters - Inspect for correct operation
and controls, if equipped.
• Fan and shroud - Check for proper operation of
fan clutch. Check installation of fan and shroud.
• Heater/water valve - Check for malfunction or
leaking. With the heat switch set to COLD, the
heater hoses should be cool.
• System ducts and doors - Check the ducts and
doors for proper function.
• Refrigerant charge - Make sure system is
properly charged with the correct amount of
refrigerant.
N4-38
TROUBLESHOOTING
Check all wires and
Operator Comfort
• Cab filters - Ensure the outside air filter and
inside recirculation filter are clean and free of
restriction.
• Condenser - Check the condenser for debris and
clogging. Air must be able to flow freely through
the condenser.
• Evaporator - Check the evaporator for debris and
clogging. Air must be able to flow freely through
the condenser.
Diagnosis Of Gauge Readings And System
Performance
Successfully servicing an air conditioning system,
beyond the basic procedures outlined in the previous
section, requires additional knowledge of system
testing and diagnosis.
A good working knowledge of the manifold gauge set
is required to correctly test and diagnose an air con-
ditioning system. An accurate testing sequence is
usually the quickest way to diagnose an internal
problem. When correctly done, diagnosis becomes
an accurate procedure rather than guesswork.
The following Troubleshooting Chart lists typical mal-
functions encountered in air conditioning systems.
Indications and or problems may differ from one sys-
tem to the next. Read all applicable situations, ser-
vice procedures, and explanations to gain a full
understanding of the system malfunction. Refer to
information listed under "Suggested Corrective
Action" for service procedures.
10/06 N04031