Air Conditioning Isn’t Just for Summer: What Drivers in Serbia Get Wrong

There is one habit shared by the vast majority of drivers in Serbia that slowly damages their car’s air-conditioning system: they switch it off in September and do not turn it on again until May. Eight months of inactivity, followed by full load on the first warm day.

This is not really the driver’s fault. It is largely because, in Serbia, car air conditioning is discussed almost exclusively in July, usually in the context of “how to survive the heat.” Few people read the owner’s manual from cover to cover, while service technicians often give advice only after a problem has already occurred. This article aims to fill that gap — with verified information rather than generic advice.

Should the A/C Be On All the Time or Only Occasionally? The Short Answer

The air conditioning should be used throughout the year, for around ten minutes at least once every 10 to 15 days — in both summer and winter.

The reason is mechanical, not related to comfort. The refrigerant circulating through the system also carries oil that lubricates the compressor. When the compressor is not running, that oil does not circulate through the system. Seals and rubber hoses can dry out, microcracks can develop, refrigerant can begin to escape, and the compressor may lack proper lubrication precisely when it is switched on under full load for the first time after winter.

That is why many A/C failures are not really summer problems. They are the result of what happened during winter — they simply become apparent in June, when workshops are busiest and prices are usually highest.

One Important Limitation in Winter

In most modern cars, the compressor will not engage when the outside temperature falls below approximately 5°C, as a protective measure for the system. This means that “turning on the A/C at minus ten” has little effect.

A practical solution is to use the air conditioning on milder winter days, or after the vehicle has warmed up — for example, toward the end of a longer journey.

In Winter, Air Conditioning Has an Important Safety Function

Air conditioning does more than cool the cabin. It also removes moisture from the air.

That is why combining heating with the A/C switched on is the fastest way to clear condensation from the windscreen. Warm air can hold more moisture, while the air-conditioning system removes that moisture from the cabin air.

Without air conditioning, the same process takes considerably longer, meaning the driver may spend more time driving with reduced visibility. In most cars, the compressor is automatically activated when the windscreen defrost or demist mode is selected for exactly this reason — even when the driver is unaware that the A/C is operating.

Who Is Legally Allowed to Service a Vehicle’s Air-Conditioning System?

The refrigerants used in automotive air-conditioning systems, such as R134a and R1234yf, fall into the category of fluorinated greenhouse gases, and their handling is regulated by law.

A person servicing motor-vehicle air-conditioning systems must hold a Certificate B issued by the Ministry of Environmental Protection, while the workshop itself must be registered with the Ministry. The certificate is valid for five years.

For drivers, the practical consequence is simple: having the A/C “recharged” by someone without the required certification is not only a question of service quality, but also of legality. Refrigerant obtained outside legal supply channels may also fail to meet its declared specifications.

You can find verified workshops offering air-conditioning services in the Car Repair Shops category on the AutoKonekt platform.

A/C Servicing: What Is Actually Done

A complete air-conditioning service is not simply a “gas top-up.” A properly performed service involves several steps:

• Evacuating the system — removing the existing refrigerant and moisture using an A/C service station, while measuring how much refrigerant was actually left in the system.

• Leak testing — using a pressure test or an electronic leak detector, with UV dye if necessary.

• Refilling the system with the exact specified quantity of refrigerant for that particular vehicle model, together with the correct compressor oil.

• Checking system pressures and outlet air temperature after refilling.

• Replacing the cabin filter and, when necessary, disinfecting the evaporator.

The amount of refrigerant recovered from the system is one of the most important pieces of information in the entire process.

If the workshop recovers significantly less refrigerant than the specified system capacity, there is a leak. Refilling the system without locating that leak is simply a waste of money — the refrigerant will escape again. The only question is whether it will take three months or a year.

Why the A/C Should Not Be Recharged Every Year

There is a widespread belief that an automotive A/C system “needs gas every season.”

It does not.

A vehicle’s air-conditioning system is a closed system designed to lose very little refrigerant during normal operation.

The SAE J2727 industry standard, which is used as a basis for regulatory requirements, specifies that leakage must not exceed 11 grams per year or 1.5% of the total refrigerant charge, whichever value is greater. In a typical system containing around 500 grams of refrigerant, this means only a few grams per year.

In practical terms: if your A/C is noticeably less effective after just one season, that is not normal wear. It indicates a fault and requires diagnosis — not simply another recharge.

The Cabin Filter — the Cheapest Part With One of the Biggest Effects

The cabin filter, also known as the pollen filter, is the one part of the system that drivers can monitor without any special equipment.

When it becomes clogged, airflow decreases and the A/C may appear weak even though the system itself is technically working correctly. Moisture and organic deposits on the evaporator can also create the characteristic unpleasant smell that appears when the system is switched on.

Bosch recommends replacing the cabin filter every 15,000 kilometres or at least once a year, while always following the vehicle manufacturer’s specifications — some models require shorter replacement intervals.

When replacing the filter, the filter housing should also be cleaned of leaves, dust and debris. Material left inside the housing continues to decompose even after a new filter has been installed.

An Unpleasant Smell From the Vents Is Not Always Caused by the Filter

If the smell remains after the cabin filter has been replaced, the most common cause is a build-up of bacteria and mould on the evaporator, which is not easily accessible.

In that case, the system needs to be disinfected — either chemically or by ozone treatment of the cabin.

Ozone treatment can also remove odours absorbed into the upholstery and seats, which is why it is often combined with deep interior cleaning.

One preventive habit costs absolutely nothing: two or three minutes before switching off the engine, turn off the A/C but leave the ventilation fan running. This allows the evaporator to dry, reducing the conditions in which mould can develop.

Deep interior cleaning and ozone treatment are offered by some partners in the Car Washes category on the AutoKonekt platform.

How Much Fuel Does Air Conditioning Really Use?

This is one of the areas where exaggeration is common in both directions.

The Swiss research institute Empa published measurements in Environmental Science & Technology showing specific figures for the additional fuel consumption caused by automotive air conditioning:

• city driving: around 10%

• suburban driving: around 2.8%

• motorway driving: around 1.3%

• annual average: around 5.4%

The logic is straightforward. The compressor requires roughly the same amount of power regardless of vehicle speed, but on the motorway the engine is producing much more total power, so the A/C accounts for a relatively small percentage of overall fuel consumption.

In city traffic, where the engine is operating at low load and frequently idling, the relative impact of the A/C is much greater.

What About Driving With the Windows Down?

This is one of those myths that is partly true.

Tests have shown that, in a smaller passenger car, driving with the windows down consumed less fuel than operating the air conditioning at maximum cooling over a speed range of approximately 64 to 113 km/h.

Only at around 129 km/h did the additional aerodynamic drag caused by open windows exceed the energy consumption of the air-conditioning system.

In practical terms: in city traffic and on ordinary open roads, open windows may be more economical; on the motorway, air conditioning is generally the better option.

In any case, the difference is usually only a few percent. Safety — particularly the driver’s ability to remain focused in high temperatures — is more important than a small fuel saving.

Air Conditioning and the Vehicle Technical Inspection

The air-conditioning system itself is not an item assessed during the vehicle technical inspection, and a faulty A/C system will not by itself cause a vehicle to fail the inspection.

However, the technical inspection does include checks of the windscreen defrosting and demisting system, as well as the cabin heating and ventilation systems.

If the blower is so weak that the windscreen cannot be properly demisted, this may be recorded as a defect — and one of the most common causes of poor airflow is a clogged cabin filter.

You can book a technical inspection with partners in the Technical Inspection category, and find cabin filters through partners in the Auto Parts category.

Five Common Beliefs That Are Wrong

“The lower I set the temperature, the faster the car will cool down.”

No. The system’s cooling capacity and fan airflow remain the same. Setting a lower target temperature simply means that the system will continue cooling for longer.

With automatic climate control, selecting LO keeps the system operating at maximum cooling output, increasing energy consumption without making the initial cooling process any faster.

“The A/C needs to be recharged every year.”

No. A properly functioning closed system loses only a negligible amount of refrigerant. If it regularly requires refilling, that is a symptom of a problem — not routine maintenance.

“Air conditioning is useless in winter.”

Quite the opposite. In winter, the A/C removes moisture from the cabin air and is one of the fastest ways to clear fogged windows. Regular operation also helps keep the compressor and system components in good condition.

“Recirculation is always better.”

Recirculation can cool the cabin faster because the system is cooling air that has already been cooled.

However, prolonged use increases humidity and carbon dioxide levels inside the cabin, which can contribute to drowsiness. On longer journeys, recirculation should therefore be switched off periodically to allow fresh air into the cabin.

“You should only switch on the A/C when you actually need it.”

That is exactly the usage pattern that can lead to the problems described at the beginning of this article.

A Quick Year-Round Reminder

• September–November: a good time to service the A/C — workshops are less busy and prices may be lower than during peak season.

• December–February: run the A/C for around ten minutes on milder days and use it to help demist the windows.

• March–April: check the system before the warm season; replace the cabin filter if a year or 15,000 km has passed.

• May–August: park in the shade when possible, ventilate the cabin before switching on the A/C, and turn the A/C off a few minutes before the end of the journey while leaving the fan running.

Frequently Asked Questions

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How often should a car’s air-conditioning system be serviced?

A complete service including a leak test is generally recommended every two to three years, while the cabin filter should be replaced once a year or every 15,000 km.

If the A/C becomes noticeably weaker before that interval has passed, the system has a fault and requires diagnosis rather than routine servicing.

Does air conditioning increase fuel consumption, and by how much?

Yes. According to measurements by the Empa research institute, additional fuel consumption is around 10% in city driving, 2.8% in suburban driving and 1.3% on the motorway, with an annual average of approximately 5.4%.

Should I use the air conditioning in winter?

Yes. It is recommended to switch it on for around ten minutes at least once every 10 to 15 days to help lubricate the compressor and preserve the seals.

At temperatures below approximately 5°C, the compressor will usually not engage, so the A/C should be used on milder winter days or once the vehicle has warmed up.

Why does the air conditioning smell unpleasant when I switch it on?

The most common causes are a clogged cabin filter and deposits of bacteria and mould on the evaporator.

The solution is to replace the cabin filter and disinfect the system. As a preventive measure, switch off the A/C a few minutes before the end of the journey while leaving the ventilation fan running.

Can any repair shop service a car’s air-conditioning system?

No. A person servicing motor-vehicle air-conditioning systems must hold a Certificate B issued by the Ministry of Environmental Protection, and the workshop must be registered with the Ministry because the work involves handling fluorinated greenhouse gases.

Can faulty air conditioning cause a vehicle to fail its technical inspection?

Not directly. The air-conditioning system itself is not an item assessed during the technical inspection.

However, the inspection does check the operation of the windscreen defrosting and demisting systems, as well as cabin heating and ventilation. Insufficient airflow may therefore be recorded as a defect.