Leak Tests

WARNING: Good ventilation is necessary in the area where A/C leak testing is to be done. if the surrounding air is contaminated with refrigerant gas, the leak detector will indicate this gas all the time. Odors from other chemicals such as antifreeze, diesel fuel, disc brake cleaner or other cleaning solvents can cause the same concern. A fan, even in a well ventilated area, is very helpful in removing small traces of air contamination that might affect the leak detector.





Checking For A/C Leaks
1. Attach high- and low-side quick disconnects to the manifold gauge set.
2. Adjust both manifold gauge valves to the maximum clockwise (closed) position.
3. Adjust both quick disconnect valves to the maximum counterclockwise (closed) position.
4. Remove A/C charging valve cap from the A/C service port fittings and install quick disconnects.
5. Adjust both quick disconnect valves to the maximum clockwise (open) position.
6. Both gauges should show approximately 413-551 kPa (60-80 psi) at 24° C (75° F) with engine not running.
7. If very little or no pressure is indicated, connect a Refrigerant R-134a cylinder to the manifold gauge set and adjust the low-pressure manifold gauge valve to the counterclockwise (open) position. This opens the system to cylinder pressure.
8. Check all system connections, the A/C compressor center seal and shaft seal for leaks using a good leak detector. Pass the leak detector along the underside of all points being checked. Refrigerant is heavier than air and will show most readily in those locations.
9. When performing leak tests of the A/C evaporator core with an electronic leak detector, test only at the evaporator drain tube and the evaporator core refrigerant line connections. Do not attempt to leak test at the instrument panel registers or inside the passenger compartment. Airflow from the blower and chemical odors inside the vehicle may cause false readings. This is especially important afier the vehicle has been sitting in the sun and the vehicle's interior temperature has risen above the ambient level.





Electronic Leak Detector
Use Rotunda R-134a Automatic Calibration Halogen Leak Detector 023-R1003 or equivalent.
^ The electronic leak detector is operated by moving the control switch to the ON position. The detector automatically calibrates itself when it is turned on.
^ Move the probe at approximately 25 mm (1 inch) per second in the suspected area. When escaping refrigerant gas is located, the ticking/beeping signal will increase in ticks/beeps per second. If the gas is relatively concentrated, the signal will be increasingly shrill.
^ Follow the instructions included with the detector to improve handling and operating techniques.





Leak Tracer Dye

NOTE: The presence of oil at A/C spring lock couplings does not always indicate a refrigerant leak. Assembly plant processes apply oil to fittings prior to connection to aid in assembly.

^ When a fitting is suspected of a leak, always wipe the fitting clean and verify the leak with an electronic leak detector or R-134a fluorescent tracer dye. To achieve accurate results, always follow the manufacturer's instructions included with the electronic leak detector or tracer dye.

NOTE: R-134a fluorescent tracer dye has been added to the A/C systems of new vehicles. Leak checking can be performed with an ultraviolet lamp and is an acceptable alternative to using an electronic leak detector.

^ The fluorescent lifespan of the leak tracer dye is 500 hours of A/C system use, after which another injection of dye is required. A/C system pressure must be above 550 kPa (80 psi) for this operation.
^ Scan all components, fittings and lines of the A/C system with Rotunda Ultraviolet Lamp 164-R0721 or equivalent. The exact location of the leak or leaks can be pinpointed by the bright yellow-green glow of the tracer dye. Since more than one leak may exist in the system, always inspect each component.
^ The best leak detection results will be achieved in conditions of low ambient light. In the areas that cannot be reached by the UV lamp: use a mechanics mirror or a non fluorescent shop towel to wipe the suspected area, and then check the towel with the UV lamp for traces of the dye.
^ After the leak is serviced, the traces of dye can be removed from the previously leaking areas by using any general purpose oil solvent.
^ Verify the service by operating the A/C system for a short while and reinspecting the system with the UV lamp.
^ Rotunda Fluoro-Lite for R-134a/PAG A/C Systems 164-R3712 or equivalent may be introduced into the A/C system using Rotunda R-134a Fluorescent Tracer Dye Injector 164-R2610 or equivalent. Inject the dye while charging the system and check for leaks as follows:
1. Adjust quick disconnect valve on dye injector to maximum counterclockwise (closed) position.
2. Remove plug from end of the dye injector reservoir and fill reservoir with 7 ml (0.25 ounces) of Rotunda Fluoro-Lite for R-134a/PAG A/C Systems 164-R3712 or equivalent.
3. Replace plug. Tighten securely.
4. Attach low-side quick disconnect from either the manifold gauge set or the charging station to the plug on the dye injector.
5. Install dye injector quick disconnect valve to low-pressure service port on vehicle.
6. Install high-side quick disconnect valve to high-pressure service port on vehicle.
7. Adjust all quick disconnect valves to the maximum clockwise (open) position.
8. Charge vehicle with the required amount of refrigerant R-134a. The flow of refrigerant through the dye injector will inject the dye into the vehicle system.
9. When vehicle charging is complete, close dye injector and high-side quick disconnect valves and remove quick disconnects from vehicle.
10. Recover refrigerant from dye injector and close low-side quick disconnect valve.
11. NOTE: The dye-injector should only be connected to the charging/ recovery station when dye is to be injected. The dye injector has a one-way check valve that will prevent system refrigerant recovery and evacuation.
Remove dye injector from low-side quick disconnect valve.
12. Using Rotunda Ultraviolet Lamp 164-R0721 or equivalent, check system for leaks. The tracer dye will glow a bright yellow/green when the ultraviolet light hits it.