Performance Diagnosis - Air Conditioning
1. Confirm that vehicle and environmental conditions are as follows.- Vehicle is not exposed to direct sun.
- Ambient temperature is within 15 - 35 °C (59 - 95 °F).
2. Make sure that high pressure valve (1) and low pressure valve (2) of manifold gauge are firmly closed.
3. Connect high pressure charging hose (3) to high pressure service valve (5) on vehicle, and connect low pressure charging hose (4) to low pressure service valve (6) on vehicle.
4. Bleed the air in charging hoses ((3), (4)) by loosening their respective nuts on manifold gauge, utilizing the refrigerant pressure. When a hiss is heard, immediately tighten nut.
CAUTION: Do not interchange high and low pressure charging hoses by mistake.
5. Warm up engine to normal operating temperature (engine coolant temperature at 80 - 90 °C (176 - 194 °F)) and keep it at specified idle speed. (Radiator cooling fan should not be working when checking pressure and temperature.)
6. Turn A/C switch ON, and set blower switch at "HI" (4th position), temperature control knob at "COOL", air outlet control knob at "FACE", fresh/circulation control knob at "CIRCULATION". (Confirm that A/C compressor and condenser fan are working.)
Performance Test Condition:
7. Keep all windows, doors and engine hood open.
8. With about 20 mm (0.8 in) of dry bulb thermometer (1) inserted into center duct air outlet and another one set near evaporator air inlet, read temperature indicated on each thermometer.
Example::
9. Check for each pressure of low side and high side if it is within shaded range of graph.
If each gauge reading is out of specified pressure, correct defective part referring to "Performance Diagnosis Table:"
NOTE: Pressure registered on gauge varies with ambient temperature. Therefore, use the graphs when determining if pressures are normal or not.
10. Check inlet port temperature-to-outlet port temperature relationship using graph.
For example, if evaporator inlet port temperature is 25 °C (77 °F) and center duct air outlet temperature is 8 °C (46.4 °F), their crossing point is within acceptable range as shown in graph.
11. If crossing point is out of acceptable range, diagnose trouble referring to "Performance Diagnosis Table:".
High Pressure Gauge:
Low Pressure Gauge:
Thermometer At Center Duct:
Performance Diagnosis Table
NOTE: If ambient temperature is within 30 - 35 °C (85 - 95 °F), it is possible to do using "Detail Diagnosis Table (at Ambient Temperature within 30 - 35 °C (85 - 95 °F)):".
Detail Diagnosis Table (at Ambient Temperature within 30 - 35 °C (85 - 95 °F))
Condition / Possible Cause:
Gauge readings, conditions, causes, and measures (classified according to malfunction symptoms) will be discussed.
Lo gauge: 0.23 - 0.35 MPa (2.3 - 3.5 kg/sq.cm) [33 - 50 psi]
Hi gauge: 1.4 - 1.75 MPa (14 - 17.5 kg/sq.cm) [200 - 249 psi]
Condition: Normal Condition
Lo gauge: Negative pressure
Hi gauge: 0.5 - 0.6 MPa (5 - 6 kg/sq.cm) [71.2 - 85.3 psi]
Condition / Possible Cause:
Lo gauge: 0.23 - 0.35 MPa (2.3 - 3.5 kg/sq.cm) [33 - 50 psi] <-> Negative pressure
Hi gauge: 1.4 - 1.75 MPa (14 - 17.5 kg/sq.cm) [200 - 249 psi] <-> 0.69 - 0.98 MPa (7 - 10 kg/sq.cm) [100 - 142 psi]
Condition / Possible Cause:
Lo gauge: 0.05 - 0.15 MPa (0.5 - 1.5 kg/sq.cm) [4.2 - 21.3 psi]
Hi gauge: 0.69 - 0.98 MPa (7 - 10 kg/sq.cm) [100 - 142 psi]
Lo gauge: 0.4 - 0.6 MPa (4 - 6 kg/sq.cm) [56.9 - 85.3 psi]
Hi gauge: 0.69 - 0.98 MPa (7 - 10 kg/sq.cm) [100 - 142 psi]
Condition / Possible Cause:
Lo gauge: 0.35 - 0.45 MPa (3.5 - 4.5 kg/sq.cm) [50 - 64 psi]
Hi gauge: 1.96 - 2.45 MPa (20 - 25 kg/sq.cm) [285 - 355 psi]
Condition / Possible Cause:
Lo gauge: 0.45 - 0.55 MPa (4.5 - 5.5 kg/sq.cm) [64 - 78 psi]
Hi gauge: 1.96 - 2.45 MPa (20 - 25 kg/sq.cm) [285 - 355 psi]