Electronic Leak Detection Method
Electronic Leak Detection MethodCAUTION: Do not operate the detector in a combustible atmosphere since its sensor operates at high temperature. Personal injury or damage to the equipment may result.
Perform a refrigerant leak test on the system whenever you suspect a leak due to the following conditions:
^ A system indication of a low charge
^ After any service operation which disturbs the following items:
- Components
- Tubes
- Connections
Many methods and special tools are available for this purpose.
TOOLS REQUIRED
J 39400-A Halogen Leak Detector
This type of leak detector is the most useful tool in locating refrigerant leaks.
There are 3 settings:
^ One for R-134a
^ One for R-12
^ One for gross leaks
The gross leak setting is for isolating very large leaks already found in one of the other two settings. Ensure that the instrument is properly calibrated, per the included instructions. Ensure that the detector is used in the proper setting for the type of refrigerant system being tested. Place the detector GAS switch in the R-134a setting prior to use.
Prior to beginning the test, ensure that the refrigerant system is sufficiently charged for leak testing by measuring the static pressure using a gauge set. System pressures above 50 psi are acceptable to conduct a leak test.
The most common leaks are found at the refrigerant fittings or connections. Leaks may result from the following conditions:
^ Improper torque
^ Damaged O-rings
^ Lack of lubricant on the O-rings
^ Dirt/debris across an O-ring
The smallest piece of lint from the following items may create a leak path along an O-ring:
^ Cotton gloves
^ Shop cloths
The successful use of this and any other electronic leak detector depends greatly upon the following conditions:
^ The scan rate
^ Carefully following the manufacturer's instructions regarding the following procedures:
- Calibration
- Operation
- Maintenance
Completely circle each joint moving at 25 to 50 mm (1 to 2 inches) per second. Ensure that the tip on the probe is as close to the surface as possible but no more than 6 mm (1/4 inch) away and without blocking the air intake. A leak is indicated when the audible tone goes from a steady 1 to 2 clicks per second to a solid alarm. Adjust the balance knob frequently in order to maintain the 1 to 2 clicks per second rate.
IMPORTANT: Halogen leak detectors are sensitive to the following items used in the vehicle:
^ Windshield washing solutions
^ Many solvents and cleaners
^ Some adhesives
Use care in order to prevent a false warning by ensuring that the surfaces are clean. Ensure that the surfaces are dry since the ingestion of liquids damages the detector. In order to ensure that no gasses are present that may cause a false warning, blow out the engine compartment using an air hose prior to the test.
Test the following areas using this procedure:
^ The pressure sensor (transducer)
^ The evaporator inlet and outlet
^ Other connections
^ All the brazed and welded areas
^ Areas showing signs of damage
^ Hose couplings
^ The compressor rear head and housing joints
IMPORTANT: Always follow the refrigerant system around in a continuous path in order to ensure that no areas of potential leaks are missed. Always test all of the above areas in order to ensure that the entire system is leak-free, even when one leak is already found.