Performance Diagnosis of A/C System

WARNING: This page is about a different car, the 2003 Suzuki XL-7 and 2003 Suzuki Grand Vitara. However, it is still accessible from the selected car via links, so may be relevant.

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).
Make sure that high pressure valve (1) and low pressure valve (2) of manifold gauge (3) are firmly closed.
Connect high pressure charging hose (4) to high pressure service valve (5) on vehicle, and connect low pressure charging hose (6) to low pressure service valve (7) on vehicle.
Bleed the air in charging hoses 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.

Fig 1: Connecting High & Low Pressure Charging Hoses
Courtesy of SUZUKI OF AMERICA CORP.
Warm up engine to normal operating temperature (engine coolant temperature at 80 - 90 °C (176 - 194 °F)) and keep it at specified idle speed.
Operate A/C at the following conditions.
- Main (front) A/C switch at ON position
- Rear A/C main switch at ON position (if equipped)
- Front blower speed selector at max position
- Rear blower motor switch at max position (if equipped)
- Air flow selector at face position
- Temperature selector at max cool position
- Vehicle door at all open
- Air inlet door at recirculation position.
Keep all windows, doors and engine hood open.
With about 20 mm (0.8 in.) of dry bulb thermometer (1) inserted into center face air outlet (2), rear A/C air outlet (4) (dual A/C model only) and near A/C evaporator air inlet, read temperature indicated on each thermometer to know temperature difference between air inlet and air outlet.

Fig 2: Reading Temperature On Thermometers
Courtesy of SUZUKI OF AMERICA CORP.
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 the table.
For Example, gauges should read as follows when ambient temperature is 30 °C (86 °F)

Pressure on high pressure gauge (HI): 1400 - 1750 kPa (14.0 - 17.5 kg/cm² , 199.1 - 248.9 psi)

Pressure on high pressure gauge (LO): 230 - 350 kPa (2.3 - 3.5 kg/cm² , 32.7 - 49.8 psi)

NOTE: Pressure registered on gauge varies with ambient temperature. Therefore, use the graphs when determining if pressures are normal or not.

Fig 3: Pressures/Temperature Relation Chart
Courtesy of SUZUKI OF AMERICA CORP.

High pressure gauge

Fig 4: High Pressure Gauge Diagnosis Chart
Courtesy of SUZUKI OF AMERICA CORP.

Low pressure gauge

Fig 5: Low Pressure Gauge Diagnosis Chart
Courtesy of SUZUKI OF AMERICA CORP.
Check inlet port temperature-to-outlet port temperature relationship using graph.
For example, if A/C evaporator inlet port temperature is 25 °C (77 °F) and center face air outlet temperature is 8 °C (46.4 °F), their crossing point is within acceptable range as shown in the graph.
If crossing point is out of acceptable range, diagnose trouble referring to the following table.

Fig 6: Inlet Port Temperature-To-Outlet Port Temperature Relationship Graph
Courtesy of SUZUKI OF AMERICA CORP.

Thermometer at center duct

Fig 7: Thermometer At Center Duct Chart
Courtesy of SUZUKI OF AMERICA CORP.
Check that difference in temperature of center face air outlet air and rear A/C air outlet air are within 5 °C (41 °F). If the rear A/C air outlet air temperature is higher over 5 °C (41 °F) than center face air outlet air temperature, check rear A/C unit.
NOTE: If ambient temperature is within 30 - 35 °C (85 - 95 °F), it is possible to do using the following table for detail diagnosis.

Fig 8: Center Face Air Outlet & Rear A/C Air Outlet Temperature Difference Diagnosis Chart (1 Of 2)
Courtesy of SUZUKI OF AMERICA CORP.

Fig 9: Center Face Air Outlet & Rear A/C Air Outlet Temperature Difference Diagnosis Chart (2 Of 2)
Courtesy of SUZUKI OF AMERICA CORP.