Help Please B8.5 S4 - Aircon not blowing cold air [emoji51]

[V6_Man]

So, it finally happened yesterday, drove the car after almost 5 weeks, hit the AC button and all it blows is hot air. There is also a grinding sound coming from the front - I can't figure out whether it is coming from behind the glovebox or under the windscreen but the noise is there.

Although most of the times the blow is absolutely fine there are instances where it feels like something is stuck and it fluctuates.

I have tried running a scan but nothing came up before I drove the car but have not been able to scan as I managed to break the laptop screen .

The grinding noise that comes can be a sign of potential blower motor failure or the compressor however I am not sure. I wanted to ask if anyone else has had any issues on their B8/B8.5s and what was fixed. I also understand that blower motor seems to be a weak link here and many have replaced it. However, if it was the blower motor wouldn't the air be not coming out at all or does it affect only cold air flow? I initially thought the pressure switch but it shouldn't make a grinding noise, should it?

Would appreciate suggestions before I book in the car. Oh, and also if there a trusted AC place you guys would recommend. I am Oxford based but don't mind traveling up to a hour either side of M40.

Thanks.

 

[rum4mo]

Maybe easier for me, as I'm not affected by this trouble, to think about it a bit more logically:- why not inhibit the chiller function and mess around with the fan blower speed and air direction to see if that also bring the grinding noises, if it does, then it is not the compressor.
I'm guessing that you do know what sort of noises an AC system that can run but is low in R134A sounds like, probably gurgling and/or screaming noises.
As for the laptop screen now not working - it never rains but it pours!!
Good Luck, in worst case get a mobile AC fixer to come to you as they tend to have lower overheads and live by their results?

 

[V6_Man]

Maybe easier for me, as I'm not affected by this trouble, to think about it a bit more logically:- why not inhibit the chiller function and mess around with the fan blower speed and air direction to see if that also bring the grinding noises, if it does, then it is not the compressor.

I have tried different fan speeds and the noise gets louder the higher you go up with 12 being max. It also gets worse when you turn the auto circulate on. I have not tried different air direction settings but have tried turning off different vents but the noise stays the same at higher fan speeds. I will try air direction settings shortly.

I'm guessing that you do know what sort of noises an AC system that can run but is low in R134A sounds like, probably gurgling and/or screaming noises.

I would have loved to say yes but not really. I did comparenit against the A3 and they both sound completely different.

As for the laptop screen now not working - it never rains but it pours!!
Good Luck, in worst case get a mobile AC fixer to come to you as they tend to have lower overheads and live by their results?

Kids had left it on the bed while I was changing the light bulb in their room. Didn't see it and stepped on the screen .

Will make a few calls tomorrow as it is the first time I will be getting an Aircon job done.

 

[rum4mo]

If you have switched off AC and are just running the fan, and it is making these noises then I'd think that it is not the AC (chiller system).
I've never ever used any AC places, well not correct, I knew that I had a slightly failed seal at a pipe join on my old 2000 VW Passat 4Motion and the VW parts listing did not list that seal accurately enough for me, so at MOT time got my VW main dealer to evac the system and replace that seal as part of their very cheap special offer of a pre Summer AC service - so what happened was, the system was roughly checked over but not a special pre Summer AC service price, lots more, and the answer was "you can't see AC leaks so we have not replaced anything" - now I used to manage the use of large systems and was certified to handle any F gases and I do know that you normally can't see AC leaks, unless they are gross leaks, but 9/10 times you can spot a build up of oil mist and that only happens if AC gas is escaping and carrying out with some of the system oil - main dealers can be idiots and normally not much good for AC gas system work/problems.

 

[V6_Man]

If you have switched off AC and are just running the fan, and it is making these noises then I'd think that it is not the AC (chiller system).

It makes the same noises with AC off as well. Reckon could just be the blower motor?

 

[rum4mo]

Yes or one of the flap motors, depending on what sort of noise there is, flap motors normally just go mad and hunt back and forwards through their limited range of travel, fan motors might make a lot more noise, maybe get the pollen filter out and see what difference that makes, though small leaves etc should not be getting past that filter, though I've forgotten where the filter is located in the air circuit.

 

[V6_Man]

Yes or one of the flap motors, depending on what sort of noise there is, flap motors normally just go mad and hunt back and forwards through their limited range of travel, fan motors might make a lot more noise, maybe get the pollen filter out and see what difference that makes, though small leaves etc should not be getting past that filter, though I've forgotten where the filter is located in the air circuit.

Makes sense. From what I gather the filter sits further back then previous models. Sounds funny but it started making the mouse after the filter was replaced at the last Service but I could be wrong - it could just be a placebo effect. Will get it checked asap.

 

[V6_Man]

So, managed to arrange a laptop and ran a scan and it appears to be the AC Pressure/Temp sensor that needs replacing. Scan below showing the fault codes - 09/03 was the last time I drove the car before disappearing on holidays.


Address 08: Auto HVAC (J255) Labels: Redir Fail!
Part No SW: 8K2 820 043 AQ HW: 8K2 820 043 AQ
Component: KLIMA 3 ZONEN H04 0122
Revision: D1000000 Serial number: 01160420140145
Coding: 6624028000
Shop #: WSC 06325 000 00000
VCID: 78F99851CBE20A8AE5-802C

2 Faults Found:
00457 - Control Module for Network (J519)
013 - Check DTC Memory
Freeze Frame:
Fault Status: 01101101
Fault Priority: 6
Fault Frequency: 5
Reset counter: 249
Mileage: 54631 km
Time Indication: 0
Date: 2019.03.09
Time: 10:50:02

00256 - A/C Pressure/Temperature Sensor (G395)
008 - Implausible Signal
Freeze Frame:
Fault Status: 01101000
Fault Priority: 7
Fault Frequency: 6
Reset counter: 0
Mileage: 54631 km
Time Indication: 0
Date: 2019.03.09
Time: 10:50:02

Freeze Frame:
Temperature: 10.0°C

 

[NevMan]

Need to get rid mate, and get yourself into RS6

 

[V6_Man]

Need to get rid mate, and get yourself into RS6

If only I could share here the actual reason why I am not going for an RS mate

 

[rum4mo]

Buying a new sensor at a dealer is the best plan as that part, or all versions of that part, seem to get updated regularly, buying NOS via an ebay seller would only mean usually buying a previous version which has been superseded for a good reason.

I'd try the guy that works for Listers or Hortons as he will give proper discount on genuine parts, you know, the one that used to operate via this site!

Edit:- one other thing, this sensor can be reached if you remove the plastic cover above the radiators, if it looks like it is a bit oily, then that faulty sensor has been leaking and so you will probably need an AC service/top up after swopping over sensors.

 

[NevMan]

If only I could share here the actual reason why I am not going for an RS mate

Go on then, PM me