Electronic Leak Detectors
Tools RequiredJ 39400-A Kent-Moore Electric Halogen Leak Detector
The J 39400-A is the most useful tool for locating refrigerant leaks. The J 39400-A is a small unit which operates on 12V DC. The J39400-A provides an audible signal which increases in frequency as one of the following refrigerants is detected:
^ R-12
^ R-134a
The J 39400-A has 3 settings:
^ R-12
^ R-134a
^ Gross
The gross leak setting is used for isolating very large leaks which you have already found using one of the other 2 settings. Ensure that the J 39400-A is properly calibrated, per the included instructions. Use the proper setting for the type of refrigerant system that you are testing. Before you begin the test, ensure that the refrigerant system is sufficiently charged for leak testing. Do this by measuring the static pressure with a gauge set. Readings in the range of 60-100 psig are acceptable in order to conduct a leak test.
The most common leaks are found at the refrigerant fittings or connections. This may be caused by one of the following conditions:
^ Improper torque
^ Damaged O-rings
^ Lack of lubricant on the O-rings
^ Dirt/debris across the O-ring
Even the smallest piece of lint from cotton gloves or a shop cloth can create a leak path across an O-ring.
In order to successfully use this leak detector, or any other electronic leak detector, perform the following steps:
^ Use the proper scan rate.
^ Follow the manufacturer's instructions regarding the following areas:
- Calibration
- Operation
- Maintenance
Use this procedure in order to test the following areas:
^ The low and high side sensors
^ The transducers
^ The switches
^ The evaporator inlet and outlet
^ The accumulator dryer inlet and outlet
^ The condenser inlet and outlet
^ Other connections
^ All brazed and welded areas
^ Areas that show signs of damage
^ Hose couplings
^ The compressor rear head
^ The housing joints
Important: Halogen leak detectors are sensitive to the following solutions that are used in vehicles:
^ Windshield washing solution
^ Solvents
^ Cleaners
^ Some adhesives
Ensure that surfaces are clean in order to prevent a false warning. Ensure that the surfaces are dry, as ingestion of liquids will damage the detector.
Always follow the refrigerant system around in a continuous path so that you do not miss any potential leak areas. Test all of the above areas in order to assure that the entire system is leak free, even when you have already found one leak.
Completely circle each joint, using the following guidelines:
^ Move at 1-2 in per second.
^ Keep the tip of the probe as close to the surface as possible.
Keep the tip not more than 1/4 in away from the surface.
Do not block the 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 in order to maintain the 1-2 clicks per second rate.