Troubleshooting By Manifold Gauge Set Readings; Insufficient Cooling; Little Or No Cooling - Komatsu 930E-2 Shop Manual

– – – TROUBLESHOOTING BY MANIFOLD GAUGE SET READINGS – – –
Possible Causes
TROUBLE: Insufficient Cooling
Indications:
Low side pressure LOW.
High Side Pressure LOW.
Discharge air is only slightly cool.
Low refrigerant charge, causing pressures to be
slightly lower than normal.
No Leaks Found:
Leaks Found:
TROUBLE: Little or No Cooling
Indications:
Low side pressure VERY LOW
High side pressure VERY LOW
Discharge Air Warm
No bubbles observed in sight glass,
may show oil streaks.
Pressure sensing switch may have compressor
clutch disengaged.
Refrigerant excessively low; leak in system.
M09010 6/97
Check for leaks by performing leak test.
1. Charge System
2. Performance Test System
1. If a leak is present at a connection, tighten the
connection, then add refrigerant as required.
2. If a system component needs to be replaced, re-
cover all refrigerant from the system. Replace
the defective part, then check the compressor
oil level; refill compressor oil as necessary.
3. Evacuate system.
4. Charge system with new / recycled refrigerant.
5. Check A/C operation and do system
performance test.
1. Add Refrigerant (make sure system has at least
50% of its normal amount) and leak test system.
2. It may be necessary to use a jumper wire to en-
able the compressor to operate, if the compres-
sor has shut down due to faulty pressure
sensing switch.
3. If a leak is present at a connection, tighten the
connection, then add refrigerant as required.
4. If a system component needs to be replaced, re-
cover all refrigerant from the system. Replace
the defective part, then check the compressor
oil level; refill compressor oil as necessary.
5. Evacuate system.
6. Charge system with new / recycled refrigerant.
7. Check A/C operation and do system
performance test.
Air Conditioning System
for HFC 134a Refrigerant
Suggested Corrective Action
M9-21