10 - 6
Air Conditioning
- System Diagnosis (cont'd)
Air in System
Gauge Readings:
Low Side Gauge -
High.
High Side Gauge -
High.
Other symptoms:
Sight Glass -
Bubbles visible during system
operation.
Pipes -
Low pressure pipes are hot to the touch.
Diagnosis:
Air is present in the system, possibly from
inadequate evacuation procedure.
Correction:
1.
Evacuate A/C system.
2.
Check compressor oil for contamination. Check
compressor for proper oil amount. Correct if
necessary.
3.
Charge system with R-134a.
4.
Operate system and check performance.
Expansion Valve Improperly M ounted or Heat
Sensing Tube Defective (Opening Too Wide)
Gauge Readings:
Low Side Gauge -
High.
High Side Gauge -
High.
Other symptoms:
Pipes -
Large amount of frost or moisture on low side
pipes.
Diagnosis:
Excessive refrigerant in low side pipes possibly
from expansion valve being opened too wide.
Correction:
1.
Leak test system.
2.
Evacuate A/C system.
3.
Repair system leaks.
4.
Charge system with R-134a.
5.
Operate system and check performance.
LOW SIDE (Blue)
HIGH SIDE (Red)
High
High
Section B
9803/3280
Section B
10 - 6
Issue 1
Fault Finding
LOW SIDE (Blue)
HIGH SIDE (Red)
High
High
LOW SIDE - 2.8 bar (2.8 kgf/cm
2
)(40 lbf/in
2
)
HIGH SIDE - 22.1 bar (22.5 kgf/cm
2
)(320 lbf/in
2
)
LOW SIDE - 3.5 bar (3.5 kgf/cm
2
)(50 lbf/in
2
)
HIGH SIDE - 22.1 bar (22.5 kgf/cm
2
)(320 lbf/in
2
)
50
40
30
30
0
10
20
60
70 80
90
100
110
120
350
150
100
500
0
50
200 250
300
350
400
450
A268070
50
40
30
30
0
10
20
60
70 80
90
100
110
120
350
150
100
500
0
50
200 250
300
350
400
450
A268080