Leaks in the air conditioning system: how to detect them?

As well as providing temperature comfort for the car's occupants, the car's air conditioning system is also excellent at removing the moisture that builds up inside the car, which can cause the windows to dew. Unfortunately, the car's air conditioning system is quite susceptible to faults and environmental influences that can lead to oxidation or other wear and tear on the system's components. The resulting fault or leak can lead to a loss of efficiency or a complete failure of the system.

Is it possible to spot an air conditioner leak by yourself?

The first sign of a reduction in air conditioning performance is an increase in fuel consumption. It can also be felt that insufficiently cool air is being blown through the ventilation grilles, even though the air conditioning system is set to run at its lowest temperature setting. A simple test of the system is sufficient to perform an initial diagnosis: set the temperature on the control panel of the air conditioner to the lowest setting and run the car engine for 5 minutes at around 2000 rpm to see how effectively the system can cool the air entering the cabin.

A professional technician who specializes in automotive and repair, says that instead of such a test, it's best to drive the car for a certain distance under normal operating conditions. If you don't get any colder air blowing into the cabin after a while, it's likely that there's a fault with the air conditioning system. The most likely and most common cause is a leak in the system.

"What else can you check yourself? As the system is quite complex and consists of several components with different functions, there is no single solution. If the system has suddenly stopped working and for some reason has become very leaky, there may be visible stains of mineral oil used to lubricate the air conditioning compressor under the bonnet, on or around the hoses. However, if there is a small leak in the system, you probably won't be able to detect it yourself," points out a specialist.

Another simple, "folk" method of checking for leaks in the A/C system is to lubricate the A/C hoses with liquid soap. Air bubbles form where the gas seeps through. However, even this method may not always be able to detect a leak in the air conditioning system.

Where are air conditioning leaks most commonly found?

The most common air conditioning leaks occur in the pressure hose connections, where they connect to the individual components of the car's air conditioning system, in the glands of the air conditioning compressor and in a damaged air conditioning radiator.

"These leaks in the air conditioning system are not so easy to detect by yourself. Special units are used to maintain air conditioning systems. They are connected via special hoses to the car's air conditioning service valves. The unit sucks out the refrigerant and oil and creates a vacuum in the system," explains the specialist.

The next step, he says, is to check the pressure build-up in the system over a given period. The higher the pressure increase, the greater the leakage in the system. This method makes it possible to detect even minimal leaks. In addition, special fluorescent dyes which glow when exposed to the ultraviolet light spectrum can be used to detect leaks.

There are other methods that help professionals to detect leaks in the air conditioning system. Special low-foaming preparations for leak detection can be used. This agent shall be sprayed on the hose joints and the connection points to the individual system components. As with soap, air bubbles indicate leakage, but this foam gives a much better result.

"Modern leak detection foams are non-flammable, biodegradable and leave no harmful chemicals behind. It is the cheapest way to detect such problems, but it cannot be classified as the most effective. If the system has already leaked most of the refrigerant, foam will not work. It will also be difficult to access all the components and hoses, where leaks may also have occurred," .

One of the most popular methods is the pressure method. In this case, nitrogen is injected into the system from a cylinder or a nitrogen generator at the maximum pressure specified by the system manufacturer (e.g. 10 bar), using maintenance valves. The system is then checked to see if the pressure level remains constant or decreases, indicating a leak.

"Professionals in garages also use special electronic sensors - devices with an electronic display and a sensor attached to a flexible probe. This device allows access to all elements of the air conditioning system, even those that are difficult to reach. The sensor detects the concentration of refrigerant in the air within a few millimeters of the A/C elements," says expert.

The electronic testers can detect even very small leaks and pinpoint their location. In some cases, the readings may be erroneous due to the evaporation of petrol or diesel, so it is recommended to carry out the check several times.

It can be concluded that in the event of a leak in the air-conditioning system, it is still unlikely that you will be able to find the refrigerant in the drain yourself, so it is advisable to entrust this task to a reliable air-conditioning service provider who not only has the specialized tools, but also the knowledge to detect this specific fault. In addition to adding refrigerant to the car's air conditioning system, such a garage will also carry out leak tests and, if necessary, repair the fault.