10 - 5
Air Conditioning
- System Diagnosis (cont'd)
No Refrigerant Circulation
Gauge Readings:
Low Side Gauge -
Zero to negative.
High Side Gauge -
Low.
Other symptoms:
Receiver-Drier -
Frost or moisture on tubes before
and after receiver-drier.
Diagnosis:
Refrigerant flow obstructed by dirt, moisture or
gas leakage from expansion valve heat sensing
tube.
Correction:
1.
Evacuate A/C system.
2.
Check heat sensing tube at expansion valve.
Replace expansion valve if necessary.
3.
Remove expansion valve and attempt removal of
dirt. If dirt cannot be removed, replace expansion
valve.
4.
Replace receiver-drier.
5.
Charge system with R-134a.
6.
Operate system and check performance.
Insufficient Cooling of Condenser or Refrigerant
Overcharge
Gauge Readings:
Low Side Gauge -
High.
High Side Gauge -
High.
Other symptoms:
Sight Glass -
No bubbles visible even at lower
engine RPM.
Diagnosis:
Refrigerant overcharge, condenser cooling fins
clogged with dirt or cooling fans malfunctioning.
Correction:
1.
Clean condenser cooling fins.
2.
Check cooling fan operation.
3.
Evacuate A/C system.
4.
Charge system with R-134a.
5.
Operate system and check performance.
LOW SIDE (Blue)
HIGH SIDE (Red)
Zero to negative
Low
Section B
9803/3280
Section B
10 - 5
Issue 1
Fault Finding
LOW SIDE (Blue)
HIGH SIDE (Red)
High
High
LOW SIDE - -1.0 bar (-1.1 kgf/cm
2
)(-15 lbf/in
2
)
HIGH SIDE - 5.4 bar (5.5 kgf/cm
2
)(78 lbf/in
2
)
LOW SIDE - 3.0 bar (3.0 kgf/cm
2
)(43 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
A268050
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
A268060
