Sentra 2007

Leak Testing

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Specific to:

Nissan Sentra 2007-2012

Perform a visual inspection of all refrigeration parts, fittings, hoses and components for signs of A/C oil leakage, damage and corrosion. A/C oil leakage may indicate an area of refrigerant leakage. Allow extra inspection time in these areas when using either an electronic refrigerant leak detector or fluorescent dye leak detector. If dye is observed, confirm the leak with an electronic refrigerant leak detector. It is possible a prior leak was repaired and not properly cleaned. When searching for leaks, do not stop when one leak is found but continue to check for additional leaks at all system components and connections. When searching for refrigerant leaks using an electronic leak detector, move the probe along the suspected leak area at 1-2 in (25 - 50 mm) per second and no further than 1/4 in (6 mm) from the component.


NOTE
Moving the electronic leak detector probe slower and closer to the suspected leak area will improve the chances of finding a leak.

Checking System for Leaks Using the Fluorescent Leak Detector

  1. Check A/C system for leaks using the UV lamp and safety goggles (J-42220) in a low sunlight area (area without windows preferable). Illuminate all components, fittings and lines. The dye will appear as a bright green/yellow area at the point of leakage. Fluorescent dye observed at the evaporator drain opening indicates an evaporator core assembly (tubes, core or expansion valve) leak.
  2.  
  3. If the suspected area is difficult to see, use an adjustable mirror or wipe the area with a clean shop rag or cloth, with the UV lamp for dye residue.
  4.  
  5. After the leak is repaired, remove any residual dye using refrigerant dye cleaner (J-43872) to prevent future misdiagnosis.
  6.  
  7. Perform a system performance check and verify the leak repair with an approved electronic refrigerant leak detector.
    NOTE
    Other gases in the work area or substances on the A/C components, for example, anti-freeze, windshield washer fluid, solvents and oils, may falsely trigger the leak detector. Make sure the surfaces to be checked are clean.


    NOTE
    Clean with a dry cloth or blow off with shop air.


    WARNING
    Do not allow the sensor tip of the detector to contact with any substance. This can also cause false readings and may damage the detector.

  8.  

Dye Injection


NOTE
This procedure is only necessary when recharging the A/C system or when the compressor has seized and has been replaced.

  1. Check the A/C system static (at rest) pressure. Pressure must be at least 50 psi.
  2.  
  3. Pour one bottle 1/4 ounce of the A/C refrigerant dye into the injector tool (J-41459).
    NOTE
    If repairing the A/C system or replacing a component, pour the dye directly into the open system connection and proceed with the service procedures.

  4.  
  5. Connect the injector tool to the A/C LOW PRESSURE side service valve.
  6.  
  7. Start the engine and switch the A/C ON and fan ON.
  8.  
  9. While the A/C is operating (compressor running), inject one bottle (1/4 ounce / 7.4 cc) of fluorescent dye through the low-pressure service valve using dye injector tool (J-41459), refer to the manufacturer's operating instructions.
  10.  
  11. With the engine still running, disconnect the injector tool from the low-pressure service valve.
  12.  
  13. Operate the A/C system for a minimum of 20 minutes to mix the dye with the system oil. Depending on the leak size, operating conditions and location of the leak, it may take from a few minutes to a few days for the dye to penetrate the leak and become visible.
  14.  

Electronic Refrigerant Leak Detector

PRECAUTIONS FOR HANDLING THE LEAK DETECTOR

When performing a refrigerant leak check, use an electronic refrigerant leak detector (J-41995) or equivalent. Ensure that the instrument is calibrated and set properly per the manufacturer's operating instructions. The leak detector is a delicate device. In order to use the leak detector properly, read the manufacturer's operating instructions and perform any specified maintenance.

  1. Position the leak detector probe approximately 3/16 in (5 mm) away from the point to be checked.

    Click image to see an enlarged view

    Fig. Position the leak detector probe approximately 3/16 in (5 mm) away from the point to be checked

  2.  
  3. When testing, circle each fitting completely with the leak detector probe.

    Click image to see an enlarged view

    Fig. When testing, circle each fitting completely with the leak detector probe

  4.  
  5. Move the leak detector probe along the component at approximately 1 to 2 in (25 to 50 mm)/sec.

    Click image to see an enlarged view

    Fig. Move the leak detector probe along the component at approximately 1 to 2 in (25 to 50 mm)/sec

  6.  

CHECKING PROCEDURE


NOTE
To prevent inaccurate or false readings, make sure there is no refrigerant vapor, shop chemicals, or cigarette smoke in the vicinity of the vehicle. Perform the leak test in a calm area (low air/wind movement) so that the leaking refrigerant is not dispersed.

  1. Turn engine OFF.
  2.  
  3. Connect a suitable A/C manifold gauge set to the A/C service ports.
  4.  
  5. Check if the A/C refrigerant pressure is at least 50 psi above 61°F (16°C). If less than specification, recover/evacuate and recharge the system with the specified amount of refrigerant.
    NOTE
    At temperatures below 61°F (16°C), leaks may not be detected since the system may not reach 50 psi pressure.

  6.  
  7. Conduct the leak test from the high side (compressor discharge to evaporator inlet) to the low side (evaporator drain hose to the compressor shaft seal). Refer to the accompanying illustrations. Clean the component to be checked and move the leak detector probe completely around the connection/component.

    Click image to see an enlarged view

    Fig. Exploded view of the refrigerant lines-2.0L engine



    Click image to see an enlarged view

    Fig. Exploded view of the refrigerant lines-2.5L engine

  8.  
  9. Perform a leak check for the following areas:


    1. Compressor
    2.  
    3. High and low-pressure hose fittings, relief valve and shaft seal.
    4.  
    5. Liquid tank
    6.  
    7. Refrigerant pressure sensor
    8.  
    9. Service valves

      Check that all the service valve caps are secure on the service valves (to prevent leaks).
       
      After removing A/C manifold gauge set from service valves, wipe any residue from the valves to prevent any false readings by the leak detector.
       

    10.  
    11. Evaporator

      With engine OFF, turn blower fan on -High- for at least 15 seconds to dissipate any refrigerant trace around the evaporator. Wait a minimum of 10 minutes accumulation time (refer to the manufacturer's recommended procedure for actual wait time) before inserting the leak detector probe into the drain hose.
       
      Keep the probe inserted for at least 10 seconds. Use caution not to contaminate the probe tip with water or dirt that may be in the drain hose.
       

    12.  

  10.  
  11. If a leak detector detects a leak, verify at least once by blowing compressed air into area of suspected leak, then repeat check as outlined above.
  12.  
  13. Do not stop when one leak is found. Continue to check for additional leaks at all system components.
  14.  
  15. If no leaks are found, perform steps 7 - 10.
  16.  
  17. Start engine.
  18.  
  19. Set the front air control as follows;
    1. A/C switch: ON
    2.  
    3. Mode: Vent
    4.  
    5. Intake position: Recirculation
    6.  
    7. Temperature: MAX cold
    8.  
    9. Blower fan speed: High
    10.  

  20.  
  21. Run engine at 1,500 rpm for at least 2 minutes.
  22.  
  23. Turn engine off and perform leak check again following steps 4 through 6 above. Refrigerant leaks should be checked immediately after stopping the engine. Begin with the leak detector at the compressor. The pressure on the high pressure side will gradually drop after refrigerant circulation stops and pressure on the low pressure side will gradually rise, as shown in the accompanying illustration. Some leaks are more easily detected when pressure is high.

    Click image to see an enlarged view

    Fig. Refrigerant leaks should be checked immediately after stopping the engine. Begin with the leak detector at the compressor. The pressure on the high pressure side will gradually drop after refrigerant circulation stops and pressure on the low pressure side will gradually rise, as shown in the graph. Some leaks are more easily detected when pressure is high.

  24.  
  25. Before connecting the recovery/recycling equipment to the A/C system, check the recovery/recycling equipment gauges. No refrigerant pressure should be displayed. If pressure is displayed, recover the refrigerant from the equipment lines and then check the refrigerant purity.
  26.  
  27. Confirm the refrigerant purity in the supply tank using the recovery/recycling equipment and the refrigerant identifier equipment.
  28.  
  29. Confirm the refrigerant purity in the A/C system using the recovery/recycling equipment and the refrigerant identifier equipment.
  30.  
  31. Discharge the A/C system using approved refrigerant recovery/recycling equipment. Repair the leaking fitting or component as necessary.
  32.  
  33. Evacuate and recharge the A/C system and perform the leak test to confirm there are no refrigerant leaks.
  34.  
  35. Conduct the A/C performance test to ensure that the system works properly.
  36.  

 
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