Compressor Malfunction; Condenser Malfunction Or System Overcharge - Komatsu 930E-2 Shop Manual

Compressor Malfunction

Indications:
Gauge Reading- Low Side High
High Side Low
The compressor may be noisy when it
operates.
Cause- Defective reed valves or other compressor
components. If the compressor is not noisy, there
may be a worn or loose compressor clutch drive belt.

Condenser Malfunction or System Overcharge

Indications:
Gauge Reading- Low Side High
High Side High
The air from the vents in the cab may be
warm.
The high pressure hoses and lines will
be very hot.
Check the engine cooling system com-
ponents, fan and drive belt, fan clutch
operation, and the radiator shutter.
Cause- The condenser is not functioning correctly or
there may be an overcharge of refrigerant inside the
system. Another possibility is lack of air flow through
the condenser fins during testing. Engine cooling
system component malfunction can cause high pres-
sure by blocking air flow (radiator shutter) or not pro-
viding air flow (fan clutch) in sufficient quantity.
M09010 6/97
Repair Procedure: If the belt is worn or loose, re-
place or tighten it and recheck system perform-
ance and gauge readings. If inspection of the
compressor is required, all of the refrigerant
must be recovered and the compressor disas-
sembled to the point that inspection can be per-
formed. Replace defective components or
replace the compressor. If particles of desic-
cant are found in the compressor, flushing of
the system will be required. It will also be neces-
sary to replace the receiver-drier. Always check
the oil level in the compressor, even if a new
unit has been installed. Rotary compressors
have a limited oil reservoir. Extra oil must be
added for all truck installations. Tighten all con-
nections and evacuate the system. Recharge
the air conditioner with refrigerant and check
the system operation and performance.
Repair Procedure: Inspect the condenser for dirt,
bugs or other debris and clean if necessary. Be
sure the condenser is securely mounted and
there is adequate clearance (about 1-1/2
inches) between it and the radiator. Check the
radiator pressure cap and cooling system, in-
cluding the fan, fan clutch, drive belts and radia-
tor shutter assembly. Replace any defective
parts and then recheck the AC system opera-
tion, gauge readings and performance.
If the problem continues, the system may be
overcharged. Recover the system refrigerant
slowly until low and high pressure gauges read
below normal. Then add refrigerant until pres-
sures are normal. Add another quarter to half
pound of refrigerant and recheck AC system op-
eration, gauge readings and performance.
If the gauge readings do not change, all of the
refrigerant should be recovered and the system
flushed. The condenser may be partially
blocked - replace condenser. Also replace the
receiver-drier or accumulator. Evacuate the sys-
tem and check operation and performance.
Air Conditioning System
for HFC 134a Refrigerant
M9-25