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A/C System Performance

  1. Confirm that vehicle and environmental conditions are as follows:
    • Vehicle is not exposed to direct sun.
    • Ambient temperature is 59-95°F (15-35°C).
  2. Make sure that high pressure valve and low pressure valve of manifold gauge are firmly closed.
  3. Connect high pressure charging hose to high pressure service valve on vehicle, and connect low pressure charging hose to low pressure service valve on vehicle. See Fig 1.
  4. 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.
  5. Warm up engine to 176-194°F (80-90°C) and keep it at 1500 RPM. On single A/C model, radiator cooling fan should not be working when checking pressure and temperature.
  6. Operate A/C at the following conditions:
    • Main (front) A/C switch in ON position.
    • Rear A/C main switch in ON position (if equipped).
    • Front blower motor switch in MAX position.
    • Rear blower motor switch in MAX position (if equipped).
    • Air outlet control button in FACE position.
    • Temperature control lever in MAX COOL position.
    • All vehicle doors open.
    • Air inlet door in RECIRCULATION position.
  7. Keep all windows, doors and engine hood open.
  8. With about 0.8" (20 mm) of a dry bulb thermometer inserted into center face air outlet, rear A/C air outlet (dual A/C model only) and near A/C evaporator air inlet, read temperature indicated on each thermometer. See Fig 2.
  9. Check for each pressure of low side and high side to see if it is within the shaded range of the graph. See Fig 3. If each gauge reading is out of specified pressure, correct defective part referring to the table. See Fig 3 and Fig 4 .
    NOTE: For example, gauges should read as follows when ambient temperature is 86°F (30°C)
    • Pressure on high pressure gauge (HI) - 199.1-248.9 psi (1400-1750 kPa).
    • Pressure on high pressure gauge (LO) - 32.7-49.8 psi (230-350 kPa).
  10. Check inlet port temperature-to-outlet port temperature relationship using the graph. See Fig 5.
    NOTE: For example, if A/C evaporator inlet port temperature is 77°F (25°C) and center face air outlet temperature is 46.4°F (8°C), their crossing point is within acceptable range as shown in the graph.
  11. If crossing point is out of acceptable range, diagnose trouble referring to the table. See Fig 5.
  12. Check that difference in temperatures of center face air outlet air and rear A/C air outlet air is within 41°F (5°C). If the rear A/C air outlet air temperature is 41°F (5°C) greater than center face air outlet air temperature, check rear A/C unit.
    NOTE: If ambient temperature is 85-95°F (30-35°C), use the Pressure Zone table for diagnosis. See Fig 6.
Fig 1: Connecting Manifold Gauges To Vehicle
G00233813Courtesy of SUZUKI OF AMERICA CORP.
Fig 2: Location Of Thermometers
G00233814Courtesy of SUBARU OF AMERICA, INC.
Fig 3: Identifying A/C Performance Table & Graph (High Pressure Gauge)
G00233815Courtesy of SUZUKI OF AMERICA CORP.
Fig 4: Identifying A/C Performance Table & Graph (Low Pressure Gauge)
G00233816Courtesy of SUZUKI OF AMERICA CORP.
Fig 5: Identifying Center Duct Outlet Temperature (Graph & Table)
G00233817Courtesy of SUZUKI OF AMERICA CORP.
Fig 6: A/C Pressure Zone Diagnosis Table
G00233818Courtesy of SUZUKI OF AMERICA CORP.
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