When the air conditioning system is no longer cooling effectively or stops working altogether, it's often due to no or too little refrigerant in the system. This is when automotive professionals are needed: before refilling the system, all leaks must be found and fixed through a leak test, as required by law for environmental protection reasons. Especially for small and very small leaks, using forming gas offers several advantages compared to other methods.
Legal regulations prohibit the refilling of a leaky air conditioning system, and rightly so, as the "old" refrigerant R134a is particularly harmful to the environment.
A leak detection test using UV light is only an option if the contrast agent was added before the leak occurred. Moreover, MAHLE views the addition of a contrast agent critically, as it reduces the lubricating properties of the compressor oil, thereby increasing the wear and tear on all components of the air conditioning system.
A time-saving, cost-effective, environmentally friendly, and particularly accurate method for leak detection is the use of forming gas. This method is effective even when refrigerant escapes slowly in gaseous form through small or very small leaks over weeks or even months.
However, this method requires that the air conditioning professional knows what to look out for.
Forming gas consists of 95 percent nitrogen and five percent hydrogen (chemical symbol H). The gas is non-toxic, non-flammable and not harmful to the environment - and can be purchased inexpensively. The leakage is then detected using an electronic leak detector - the sniffer.
The hydrogen serves as a trace gas to which the electronic sniffer reacts in the event of a leak. Hydrogen atoms are the smallest in the universe and extremely volatile, which makes them ideal for detecting microleaks. This is because the smaller the gas molecules are, the more will escape at a leak. And the more gas escapes, the easier and quicker it is to locate the leak.
The leak detection kit can be connected directly to MAHLE ArcticPRO® units. connected directly. After evacuating the remaining refrigerant, the system is filled with forming gas. filled with forming gas. The hydrogen penetrates even the smallest leaks, which can then be localized with the sniffer. As hydrogen is lighter than air, the sniffer sensor must always be positioned above the the area to be tested.
Tip: Initially only pressurize the refrigerant circuit to a low pressure (maximum 2 bar) and start the leak detection at the compressor shaft seal.
Because underused air conditioning systems in particular suffer from creeping refrigerant losses. During longer downtimes, for example over the winter season or when fuel is to be saved, no refrigerant circulates - and therefore no refrigerant oil. As a result, the sealing lip of the sealing ring is not sufficiently lubricated and eventually hardens. And as long as there is pressure in the system, refrigerant can leak out gradually.
If you were to test with a higher pressure straight away, the sealing lip can set and seal so that the sniffer does not strike.
If the sniffer is silent when the test pressure at the compressor sealing ring is low, the air conditioning professional increases the test gas pressure in stages, for example in steps of 5 bar, up to the maximum pressure permitted by the vehicle manufacturer and repeatedly checks the tightness of all system components after each step until he has found the leak.