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TSB 241394

R134a Refrigerant Leak Detection

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MODELS: 1994 1995 (BR) Ram Truck

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 15C (59F), 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.


Thanks to Bob Bergevin and Barry Drodge for supplying this TSB information

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This page was edited on: May 3, 2004