Seven methods for detecting A/C system leaks

WAECO explain how choosing the right leak detection method is crucial for efficient and effective A/C system repair

Seven methods for detecting A/C system leaks

Finding leaks in A/C systems can be time consuming, but knowing which method is best and when to use it can help you find leaks quicker.

1 UV LEAK DETECTION

A special, fluorescent additive is injected into the refrigerant circuit – either via the A/C service unit or manually. Some new drier models are already fitted in the factory with such additives. When the A/C components are illuminated with a UV lamp and viewed through yellow UV protection goggles, the leak appears brightly lit up. Visibility is ensured even where oil-covered engines are concerned and even at some distance. Unlike the forming gas method, UV leak detection is also suitable for tracing ultra-fine leaks. Where vibration leaks are concerned it is the only method available.

2 NITROGEN

This method involves the production of positive pressure through nitrogen or negative pressure through vacuum by the A/C service unit. Leak detection through differential pressure is mainly suitable for the initial testing of strongly leaking or even empty systems. It only indicates that the system is leaking – not where the leak is. Testing is only possible with A/C service units that automatically stop when it is impossible to generate vacuum (e.g. all WAECO ASC service units). If the process continues without fault warning, you can be certain that the system has no leak and may be charged with refrigerant. The requirements of the Chemicals Climate Protection Ordinance are met.

3 TRACER OR FORMING GAS

Forming gas consists of 95% nitrogen and 5% hydrogen. The operating principle is similar to that of electronic leak detection. The difference is that the operator has to fill the system with test gas when the refrigerant has been removed. The drawback of this method is the length of time required (after 15 minutes the hydrogen has almost completely diffused and must be replaced). Another disadvantage is the fact that testing takes place when the system is not operating. “Vibration leaks” which occur while the engine is running can therefore not be detected. (The system needs refrigerant to operate, but it cannot be recharged yet because of the leak!) Moreover, leak detection with forming gas requires clean and constant ambient conditions (for example no draughts in the workshop).

4 ELECTRONIC LEAK DETECTION

Finding very small leaks is no problem for electronic leak detection systems. In some sections of the A/C system it is difficult though to apply the probe correctly, or at least very time-consuming.

5 VACUUM CHECK

Fully automatic with A/C service units include a vacuum phase. If there is a leak in the A/C circuit, it is not be possible to create a vacuum and the ASC will stop the procedure.

6 SIMPLE BUBBLE TEST

Looking for a leak with lather, the so-called “bubble test”, belongs to the oldest methods of leak detection. It has become almost insignificant, however, as it is impossible to find very small leaks using this method.

7 ULTRASONIC LEAK DETECTION

Ultrasonic leak detectors, as the name suggests, identify the sound waves emitted when a refrigerant gas escapes through a leak. The sound is well above the frequencies audible to the human ear. Ultrasonic leak detectors measure the sound level and indicate the corresponding degree of leakage (typically by several LEDs and an additional warning tone). Fitted with an internal noise control system, ultrasonic leak detectors are unaffected by ambient noise, so they are also reliable in noisy workshop surroundings.

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