32 SECTION 50 - CAB HEATING AND AIR CONDITIONING
EXAMPLES OF MANIFOLD GAUGE READINGS AND INTERPRETATIONS
The following examples show typical low and high pressure gauge readings obtained when performance test-
ing the air conditioning system with an ambient temperature of 35 °C.
The recommended corrective action is based on a similar fault as identified in the performance test diagnosis
charts.
PERFORMANCE TEST EXAMPLE 1
Performance Test Example 1
1. High side low
2. High side hand valve closed
3. High side hose connected to high side service
connector
4. Not used
5. Low side hose connected to low side service
connector
6. Low side hand valve closed
7. Low side low
PROBLEM
Little or no cooling.
CAUSE
Refrigerant slightly low.
CONDITIONS*
Low side pressure too low.
Gauge should read 1-2 bar.
High side pressure too low.
Gauge should read 13.3-14.8 bar.
Evaporator air not cold.
CORRECTIVE PROCEDURES
1. Leak test the system.
2. Repair leaks. (Discharge and recover the refrig-
erant from the system; replace lines or compo-
nents).
3. Check compressor oil to ensure no loss.
4. Evacuate the system.
5. Charge the system.
6. Performance test the system.
DIAGNOSIS
System refrigerant is low. May be caused by a small
leak.
NOTE: * test procedure based upon ambient tem-
perature of 35 °C.
For proper high side gauge reading for other ambi-
ent temperatures, refer to the pressure temperature
chart.
F28697
1
2
3
7
6
5 4
To Next Page
Loading...
