Leak Detection

A/C technicians use several different methods to help pinpoint where the refrigerant is leaking from in an A/C system. The most cost-effective method to locate a hard to find or suspected leak is to add a special dye to the A/C system. This dye is often difficult or even impossible to see with the naked eye, but will glow brightly when illuminated by an ultraviolet (UV) light. To discover where your suspected refrigerant leak is coming from, UV dye is added when servicing your air conditioning system.

Several weeks after servicing or when a reduction in cooling has been observed, a special UV light should be shone around the engine bay of your vehicle, focusing on the air condition lines around the ac compressor and the ac condenser at the front of the car. If the leak still hasn’t been found it may be necessary to check inside your vehicle under the dash. The evaporator is located under the dash assembly. This may be more difficult to find whilst the dash is still assembled but dye may be present in the air vents, on the carpet, on the cabin air filter or on the drain tube.

Another method of leak detection is using a Nitrogen Leak Detector. With this nitrogen leak test procedure, the A/C technician first removes any remaining refrigerant and pumps compressed nitrogen into the refrigeration system. The leaks become audible because the nitrogen is held at a higher pressure than the refrigerant operates under normal conditions. Imagine when you pump air into your bicycle tire, and you can hear the air coming out. It’s the same concept here.

In addition to listening for audible signs of a leak, and A/C technician will also watch the pressure gauges to see if there are any changes in pressure. In a system without leaks, pressure will remain constant. A system with a leak will show fluctuations. The downside to a nitrogen test is it may not be a very effective method of finding leaks if they are very slow. The larger the leak in the A/C system the better the odds that a nitrogen test will be able to locate and pinpoint the leak.

A third option used by A/C technicians to help pinpoint a leak in the A/C System is using a special bubbling agent. The special mix is sprayed over the components of the air conditioning system and any leaks will be shown as bubbling.

There are no right or wrong methods to find leaks, however the best method is usually determined on a case-by-case basis. Technician experience can dramatically narrow down the time taken to find a leak because certain vehicles are known to be prone to leak from particular areas which the technician would then focus on.