Electronic Leak Detectors

Electronic Leak Detector J 39400:

A/C Leak Scan Method:

Tool Required:
J 39400 Electronic Leak Detector

Electronic leak detectors have been found to be the most useful tool in locating refrigerant leaks. The J 39400 is a small unit which operates on 12V DC current and provides an audible signal which increases in frequency as R-134a is detected. There are three leak size settings: one for R-12, one for R134a, and one for gross. The gross leak setting is for isolating very large leaks already found in one of the other two settings. The instrument must be properly calibrated according to the manufacturer's instructions. The detector must be used in the proper setting for the type of refrigerant being tested.

The most common leaks are found at the refrigerant fittings or connections. This may be caused by improper torque, damaged O-rings, lack of lubricant on the O-rings, or debris across the O-ring. Even the smallest piece of lint from cotton gloves or shop cloths can create a leak path across an O-ring.

The successful use of this or any other electronic leak detector depends greatly upon the scan rate and upon carefully following the manufacturer's instructions regarding calibration, operation and maintenance. Each joint must be completely circled, moving at 25 to 51 mm (1 to 2 inch) per second, with the tip of the detector probe as close to the joint as possible. The detector must not be further than 6.1 mm (0.25 inch) away from the joint without blocking the probe's air intake. A leak is indicated when the audible tone goes from a steady 1 to 2 clicks per second to a solid alarm. The balance knob should be adjusted frequently to maintain the 1 to 2 clicks per second rate.


Important

^ Halogen leak detectors are sensitive to windshield washer solvent, many other solvents, cleaners and some adhesives. Care should be taken to prevent a false warning by making sure all surfaces are clean. Also, surfaces should be dry since ingestion of liquids will damage the detector. To assure no gases are present that may cause a false warning, blow out engine compartment with air hose prior to test.

All A/C component pipe/hose connections along with the inlet and outlet pipes/hoses for all A/C components can easily be tested using this method.


Important

^ Always follow the refrigerant system around in a continuous path so that no leaks are missed. Always test all the above areas to assure the entire system is leak free, even when one leak is already found.

CAUTION: Care must be taken to prevent personal injury which could occur due to touching a hot engine when testing. Tests should be done with the engine oft and as cool as possible. Do not operate the detector in a combustible atmosphere since its sensor operates at high temperatures.