Komatsu 830E-AC Shop Manual page 965

TROUBLESHOOTING BY MANIFOLD GAUGE SET READINGS
PROBLEM: Insufficient Cooling
Indications:
Low side pressure - LOW.
High side pressure - LOW.
Discharge air is only slightly cool.
Possible Causes
- Low refrigerant charge, causing pressures to be
slightly lower than normal.
PROBLEM: Little or No Cooling
Indications:
Low side pressure - VERY LOW
High side pressure - VERY LOW
Discharge air is warm.
No bubbles observed in sight glass, may show oil
streaks.
Possible Causes
- Pressure sensing switch may have compressor
clutch disengaged.
- Refrigerant excessively low; leak in system.
N04031 10/06
Suggested Corrective Actions
Check for leaks by performing leak test.
If No Leaks Are Found:
Recover the refrigerant and use a scale to
charge the proper amount into the system.
Check system performance.
If Leaks Are Found:
After locating the source of the leak, recover the
refrigerant, and repair the leak. Evacuate the
system and recharge using a scale. Add oil as
necessary. Check A/C operation and perform-
ance test the system.
Suggested Corrective Actions
Add refrigerant (make sure system has at least
50% of its normal amount) and leak test system.
It may be necessary to use a jumper wire to
enable the compressor to operate, if the com- -
pressor has shut down due to faulty pressure
sensing switch. Repair any leaks and evacuate
the system if necessary, Replace the receiver-drier
if the system was opened. Recharge the system
using a scale and add oil as necessary. Check
A/C operation and do system performance test.
Operator Comfort N4-39