No cold air from the air con is a very common complaint among owners of the Audi A5. Refrigerant leaks, faulty sensors and faults in flap motors mean the climate control system does not do its job, especially in models from 2008 onwards. The good news: most problems are relatively easy to diagnose. With the right approach you can fix them quickly.
Why the air con doesn’t cool in the Audi A5
The climate control system in the Audi A5 often suffers from three main causes. These make cooling impossible. Many owners report these problems. They occur in various model years.
The most commonly reported fault is a defective pressure and temperature sensor. This is sensor G395. This sensor measures the pressure and temperature in the cooling system and passes that information on to the compressor (the air con pump) and cooling fan. If it fails, the sensor no longer sends a signal. The compressor then does not engage. You recognise this from fault code 00256 on an OBD scanner (a diagnostic device for fault codes). You often see code 00457 at the same time, which points to a communication problem with the AC control unit J519.
A second very common cause is refrigerant leakage or incorrect filling. Low refrigerant levels prevent cooling altogether, while too much refrigerant can actually damage the compressor. Leaks often arise from ageing seals. Small cracks in hoses or a damaged condenser (the component that cools the refrigerant) are also common. Regular servicing and checking of the seals helps prevent this.
In models from 2017 to 2019, problems with flap motors are particularly frequent. Flap motors control the airflow in the system. They operate the recirculation flap (which reuses air from the cabin) and the fresh-air flap (which draws in outside air). When a mechanical fault occurs, the airflow is blocked so no cold air reaches the cabin. You recognise this from fault codes B109207 and B11AF07. The specific part 4M0 820 511 A is often the culprit in these model years.
‘ Replace the cabin filter every year to prevent this. ’
Common air con faults with the Audi A5 in summer
In the warmer months, certain air con faults become particularly noticeable. The compressor has to cope with higher demand in hot weather and may fail if it is worn or internally damaged. A dirty or blocked condenser also reduces cooling capacity. The condenser is located at the front of the car and catches a lot of dust, leaves and insects, which obstructs heat exchange.
In addition, the blower motor (the interior fan) can become weak due to prolonged use. Do you feel little airflow, even on the highest setting? That often points to a poorly functioning blower. A blocked cabin filter (the filter that cleans the interior air) can also be the cause. Replace the cabin filter annually to prevent this.
Electrical faults such as blown fuses or faulty relays also occur, especially after intensive use. Fuses protect electrical circuits. Relays switch electrical components on and off. Check the simple parts first before looking for complex causes. A blown fuse costs little and is quick to replace.
Air conditioning repair costs for the Audi A5
The costs for air con repair vary greatly depending on the type of fault. Replacing sensor G395 is relatively affordable. The part costs between €50 and €100. Aftermarket sensors also work well. Owners report good experiences with these. Including labour time you are looking at a total amount between €150 and €250 at a garage.
For refrigerant leaks you need to take two components into account. First, the leak must be detected. Second, the system must be refilled. A regas service costs between €75 and €150, but if the leak is large and parts need to be replaced, the bill rises more quickly. Replacing hoses or seals can cost between €200 and €400, depending on their location and accessibility.
A faulty compressor is the most expensive. A new compressor including fitting costs between €600 and €1,200. For a flap motor fault, especially on the 2017–2019 models, you should expect €200 to €400 for the part and labour.
Preventive maintenance is considerably cheaper. An annual leak test and system check usually costs between €50 and €100. According to owners and mechanics, this prevents roughly 80 per cent of faults.
Refilling the air con yourself on the Audi A5
It is possible to top up the refrigerant yourself with a regas kit from a motor factor, but this carries risks. The most important warning is: overfilling damages the system and can cause the compressor to fail. The correct pressure level is critical for a properly functioning climate control system.
Professional equipment measures the exact amount of refrigerant and checks for leaks at the same time. When you work on it yourself, that precision is missing. Is there a leak in the system? Topping up only solves the problem temporarily. The refrigerant will leak away again and you will have to top up again, which is costly and harmful to the environment.
Also pay attention to the correct type of refrigerant. The Audi A5 uses R134a or, on newer models from around 2017, R1234yf. These are both types of refrigerant gas. They are not interchangeable. If you use the wrong type, you will damage the system and repairs can run into the hundreds of euros.
For a reliable diagnosis, a professional inspection is advisable. A garage uses an OBD scanner (a diagnostic device for fault codes) to read fault codes. The garage also measures the pressure. A garage will also trace any leaks using special UV fluid or electronic detectors. This gives certainty about the cause and prevents unnecessary costs.
‘ Codes such as 00256, 00457 or B109207 point directly to specific components. ’
Diagnostic tips for air con problems
Always start with a scan using an OBD device to read fault codes. Codes such as 00256, 00457 or B109207 point directly to specific components. With code 00256 the problem lies with sensor G395, which is located on the high-pressure side near the condenser. Replace the sensor and reset the code. Many owners report that the compressor engages immediately afterwards.
Then check the refrigerant pressure. If it is normal, test the compressor and fan. Is the pressure good but the compressor and fan do not engage? Then the problem lies with the electrical connections, the compressor itself or the control unit (the control unit for the air con system). Inspect cables, connectors and relays for corrosion or loose contacts.
Clean the condenser regularly and inspect the cabin filter. A blocked condenser or filter significantly reduces cooling and is easy to fix. On models from 2017–2019 with flap motor issues, the specific part must be replaced. This is a known defect on the A5 and related Audi models.
Prevention and maintenance of the climate control system
Regular maintenance prevents most air con faults. Replace the cabin filter every year, especially if you often drive on dusty roads. Check the seals and hoses for cracks or signs of wear. You can sometimes spot small leaks from oil stains around joints.
Also run the system for a few minutes now and then in winter. This keeps the seals supple and prevents the refrigerant from solidifying or settling. An annual leak test at a garage gives clarity about the condition of the system. This costs little compared with major repairs.
If you hear strange noises when switching on the air con, have this checked immediately. Rattling or clicking can indicate a compressor that is wearing out. Early replacement prevents further damage to the cooling system and ultimately saves money.
More information about Audi A5 problems
Air con faults are only one aspect of the technical points of attention on the Audi A5. On the Carnews website you will find extensive information about other common problems, maintenance tips and owner experiences. Discover more about your Audi and stay up to date with practical solutions for car problems.
Frequently asked questions
You can recognise the most common air con faults in an Audi A5 by the lack of cold air while the air con is switched on, often caused by a defective pressure/temperature sensor (G395) or a refrigerant leak. With sensor problems the compressor and cooling fan do not engage, and fault codes such as 00256 or 00457 are stored. With leaks or incorrect filling you usually notice reduced or fluctuating cooling, sometimes after a previous “top-up”. Sticking flap motors or dirty filters/condenser are recognised by weak or uneven airflows from the vents and sometimes clicking or humming noises behind the dashboard.
Typical causes of air con problems in an Audi A5 are defective pressure/temperature sensors (such as G395), refrigerant leaks or incorrect filling, sticking flap motors for air flaps, and faults in the compressor, blower or electrical control. These lead to no cold air, poorly functioning air distribution or warning messages. You can prevent them by replacing the interior filter annually, having the air con regularly checked for leaks and refrigerant level, and keeping the condenser/evaporator clean. In the event of faults, always have the fault codes read and have suspicious sensors, flap motors and wiring checked in good time and replaced if necessary.
The estimated costs for fixing air con faults in an Audi A5 vary greatly depending on the type of problem. Replacing a pressure/temperature sensor (G395) is relatively inexpensive and usually comes to a few hundred euros including labour, while tracing and repairing refrigerant leaks (with a refill) can quickly head towards several hundred euros. Problems with flap motors or mechanical parts in the ducting system can, depending on accessibility and required parts, rise to several hundred to well over a thousand euros. Major repairs such as replacing the compressor or blower are among the most expensive jobs and are often in the high hundreds to well over one thousand euros.
Small jobs such as replacing the interior filter, visually checking and cleaning the condenser, and replacing an easily accessible G395 pressure sensor with the correct OBD reset can usually be done yourself. As soon as there is a refrigerant leak, or topping up or draining the refrigerant is required, or if the compressor, flap motors or electronics are suspected to be faulty, a visit to the garage is necessary. If fault codes keep coming back (for example 00256 or B109207) despite your own efforts, the car should be connected to a specialist’s diagnostic equipment. If you are unsure about pressure values or the correct quantity of refrigerant, always go to the garage.
A faulty air conditioning system in an Audi A5 significantly reduces driving comfort because the cabin is not properly cooled, the windows mist up more quickly and the air quality deteriorates. With some faults, such as sensor or flap motor problems, the airflow can become uneven or restricted, making the in-car climate unpleasant. In extreme cases, an overloaded or seizing compressor can create extra mechanical resistance, increasing fuel consumption and slightly reducing performance. Indirectly, the driver’s concentration may also decrease at high temperatures, which further negatively affects driving comfort and safety.