DISCUSSION:
R­134a refrigerant leaks are more difficult to detect than R­12 because of the smaller molecular structure. Listed below are the R­134a leak detection units currently approved by Chrysler and SAE:

HITECH Instruments Models HI 300 TEL, HI350,
HI 400 NOVA TEL, and HI 450 NOVA
Leybold Inficon Models HLD4000 and D/TEC
OTC/Yokogawa Model H1ON

NOTE: LEAK DETECTOR PROBES ARE VERY SENSITIVE TO CONTAMINANTS DO NOT EXPOSE PROBES TO LUBRICANTS PAINT, WELDING AND MASTIC FUMES, VEHICLE FUEL, EXHAUST OR COOLANT, HALOGENATED SOLVENTS, CHLORINATED WATER OR STEAM, DUST, POWDER. OR DIRECT STREAMS OF R­12 OR R134a
ANY TIME CONTAMINATION IS VISUALLY PRESENT ON THE PROBE, OR THE PROBE IS SUSPECTED OF BEING NEAR A CONTAMINANT FOLLOW THE MANUFACTURERS RECOMMENDATION FOR CLEANING OR REPLACING THE FILTER/SENSOR. ONLY A PROPERLY MAINTAINED LEAK DETECTOR WILL PROVIDE ACCURATE LEAK DETECTION.

TECHNICIAN PROCEDURE FOR USING ELECTRONIC REFRIGERANT LEAK DETECTORS FOR SERVICE OF MOBILE AIR CONDITIONING SYSTEMS
SAE Recommended Practice J1628
1. The electronic leak detector shall be operated in accordance with the equipment manufacturer s operating instructions.
2. Leak test with the engine not in operation.
3. The air conditioning system shall be charged with sufficient refrigerant to have a gauge pressure of at least 340 kPa (50 psi) when not in operation. At temperatures below 15°C (59°F), leaks may not be measurable since this pressure may not be reached.
4. Take care not to contaminate the detector probe if the part being tested is contaminated. If the part is particularly dirty, it should be wiped off with a dry shop towel or blown off with shop air. No cleaners or solvents shall be used, since many electronic detectors are sensitive to their ingredients.
5. Visually trace the entire refrigerant system and look for signs of air conditioning lubricant leakage, damage, or corrosion on all lines, hoses, and components. Each questionable area should be carefully checked with the detector probe, as well as all fittings, hose to line couplings, refrigerant controls, service ports with caps off, brazed or welded areas, and areas around attachment points and hold­downs on lines and components.
6. Always follow the refrigerant system around in a continuous path so that no areas of potential leaks are missed. If a leak is found, always continue to test the remainder of the system.
7. At each area checked, the probe should be moved around at a rate of no more than 25 to 50 mm/s (1 to 2 inches/second), and no more than 5 mm (1/4 in.) from the surface completely around the position. Slower and closer movement of the probe greatly improves the likelihood of finding a leak.
8. An apparent leak should be verified at least once by blowing shop air into the area of the suspected leak, if necessary, and repeating the check of the area. In cases of very large leaks, blowing out the area with shop air often helps locate the exact position of a leak.
9. Leak testing of the evaporator core while in the air conditioning module should be accomplished by turning the air conditioning blower on high for a period of 15 seconds minimum, shutting it off, then waiting for the refrigerant to accumulate in the case for time specified by 9.1, then inserting the leak detector probe into the condensate drain hole if no water is present, or into the closest opening in the heating/ventilation/air conditioning case to the evaporator, such as heat duct or vent duct. If the detector alarms, a leak apparently has been found.
NOTE: R134a REFRIGERANT IS HEAVIER THAN AIR AND WILL TEND TO STAY LOW IN THE A/C MODULE.
9.1 The accumulation time shall be specified by the leak detector manufacturer in the instructions included with the detector, or a minimum of 2 minutes.
10. Following any service to the refrigerant system of the vehicle, and any other service which disturbs the refrigerant system, a leak test of the repair and of the service ports of the refrigerant system should be done.

NOTE: CURRENTLY THERE IS NO CHRYSLER APPROVED R­134a REFRIGERANT LEAK DETECTION DYE AVAILABLE USE OF AN UNAPPROVED DYE WILL CAUSE DAMAGE TO THE A/C SYSTEM. AN APPROVED DYE WILL BE AVAILABLE IN THE NEAR FUTURE.

POLICY: Information Only