Electronic Halogen Leak Detectors
ELECTRONIC HALOGEN LEAK DETECTORA/C Leak Scan Method:
Tool Required: J-39400 Halogen Leak Detector
This type of leak detector has been found to be the most useful tool in locating refrigerant leaks. The J-39400 is a small unit which operates on 12V DC and provides an audible signal which increases in frequency as R-134a (which is used in this vehicle), or R-12 is detected. There are three settings:
^ R-134a
^ R-12
^ Gross
The gross leak setting is for isolating very large leaks already found in one of the other two settings. Care must be taken that the instrument is properly calibrated, per the included instructions, and that the detector is used in the proper setting for the type of refrigerant system being tested. The detector "Gas" switch should be placed in the "R-134a" setting prior to use.
Prior to beginning the test, make sure the refrigerant system is sufficiently charged for leak testing by measuring the static pressure with 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. This may be caused by improper torque, damaged O-rings, lack of lubricant on the O-rings, or dirt/debris across an 0-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 and 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 1-2 inches per second with the tip on the probe as close to the surface as possible but no more than 1/4" away and without blocking air intake. A leak is indicated when the audible tone goes from a steady 1-2 clicks per second to a solid alarm. The balance knob should be adjusted frequently to maintain the 1-2 clicks per second rate.
CAUTION: Halogen leak detectors are sensitive to windshield washing solutions, many solvents and cleaners, and some adhesives used in the vehicle. Care should be taken to prevent a false warning by making sure 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 reading, blow out engine compartment with air hose prior to test.
The pressure sensor (transducer), evaporator inlet and outlet, receiver/dehydrator inlet and outlet, condenser inlet and outlet, other connections, all brazed and welded areas and areas showing signs of damage, hose couplings, and the compressor rear head and housing joints may be tested using this procedure.
CAUTION: Always follow the refrigerant system around in a continuous path so that no areas of potential leaks are missed. Always test all the above areas to assure the entire system is leak free, even when one leak is already found.