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Audi Specialist Macclesfield

Audi A6 Air Conditioning Not Working

Imagine driving along in your Audi A6, designed as an executive car, and it is a rare hot, sunny day in the UK and you press your air conditioning button.  The light comes on, you set the temperature to 16 degrees but you notice immediately that it isn’t getting cooler.  There is nothing happening. 

Now imagine your frustration if this wasn’t the first time you’d had the issue, you thought it had been fixed but here it was happening again!

This is what happened to one of our clients in Macclesfield.  He brought his 2016 Audi A6 to us after a dealer had reviewed the issue and provided a (rather significant ££!) quote to complete the work. 

What’s more Mr Hutchinson wasn’t highly confident in his old garage being able to fix the problem given that it had been to them previously for what looked like the same issue. 

Let’s face it, it’s totally frustrating when you think something is fixed, and you don’t find out otherwise until you need it.  Nothing worse than being on your way to a business meeting, needing the air conditioning and it doesn’t work.  Leaving you a sweaty, irritated mess when you arrive.  Not the best look.

So having heard that Links’ technicians are Audi experts, the client called us to arrange an initial diagnostic appointment.

Working with Audi error codes

Knowing that this Audi A6 had recently been taken in for a service and the problem was not identified or fixed, we needed to start from the very beginning.    One of our expert Audi technicians took on the job, seeing it through from start to finish.  We started with a visual check of the car, followed by all the initial service checks, incorporating an Air Conditioning service check.

This initial assessment gave us a difference between the refrigerant pressure reading within the air conditioning electronics, compared to what was actually within the system.  We were able to confirm that the amount in the system was correct, so we needed to find out the reason between two different readings.  Realising we needed to complete further diagnostic analysis, we informed the client we needed more time and he booked the Audi A6 in for a full diagnostic appointment.

What are the options?

Now having the car booked in for further analysis, means we got to spend a bit more time on ruling out what was working and what needed fixing.  With our experience and knowledge, we turned to our ELSA technical information (the same technical information that the Audi dealers use) and all the wiring diagrams for the Audi A6 model, and we were able to confirm the following Audi Error Codes:

  • 00256 – Air Conditioning Pressure/Temperature Sensor
  • G395 – No Signal/Communication

We needed to narrow it down further… Time for the process of elimination.  So we knew that the Air Conditioning refrigerant quantity was good, which highlighted that we needed to check the sensors and wiring within the AC system.  Using our in house oscilloscope, our Audi technician started by checking the  pins in the plug of the pressure sensor.  We were  able to confirm that the live and earth wires were active and working, but there was no communication waveform from the check.

The pressure sensors use a LIN (Local Interconnect Network) to allow the pressure reading to be communicated back to the unit.  Another sensor is on the same network, but this one tested 100% working.  So knowing that the signal coming OUT of the Air Conditioning unit was working fine, we were able to pinpoint the problem to a wiring defect on the first sensor.  All was confirmed with a quick oscilloscope and waveform check.

So now… let’s chill

Knowing the fault was in the LIN communication wire, our Audi technician used his knowledge and expertise (and a little help from the Audi A6 official wiring diagram) to trace the wire from start to finish.  Being able to identify a good signal at both plugs, meant the fault had to be somewhere along the way.  Tracing the wire along past the passenger B pillar plug showed that the problem had to be between the sensor and the Pillar B plug….  

Narrowing it down to between these two points allowed the wire to be traced over the passenger wheel arch and then down under the front left headlight.  Those wiring diagrams are essential when it comes to tracking a wiring fault.

Having gained access to the loom, it was easy to spot a corroded piece of wire in the NSF corner of the Audi A6.  Even with the corrugated protection tube in place the corrosion was enough to stop all communication between the sensors.

With a replacement section of wire installed, and making sure to remove all the faulty wire and checking that the corrosion hadn’t spread further along the wire, we were able to run an updated check on the whole unit.  The pressure reading was back to normal, sensors reading properly and the in car Air Con unit was working again.

As well as keeping our client cool during the Macclesfield summer, our extensive Audi knowledge, access to state of the art dealer tools and comprehensive electronics know-how allowed us to make a quick diagnosis and get the car back to the client repaired as soon as possible.  Our speedy resolution and our competitive rates not only saved the client a sweaty shirt, but also saved on their wallet.

Do you need our help?

If you are experiencing a problem with your Audi, or you just need some advice please contact one of our expert technicians where we will be happy to answer your queries, or book you in for a diagnostic appointment.

Our vehicle assessments are designed to identify the problem and get it resolved as soon as possible, saving you time and money.

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