My 911 Carrera 63 Reg - Intermittant High Pitch noise - Page 3 - Porsche General - PistonHeads UK

I bought a 911 in October 2021 from a main Porsche dealer. A few weeks after purchase I could hear a high pitch screeching noise seemingly emanating from the PCM screen but it quickly disappeared. Since then the noise remains but only heard on an intermittantl basis, i.e weeks can pass without hearing it. The noise has a mind of its own but it only starts when I reach 49mph and continues in higher speeds. It can be heard with the soundsystem on or off. The vehicle is still under warranty and I have taken the car to the dealer I bought the car from and another Porsche dealer who is closer to where I live. However, after testing neither could not hear the noise. Although I made a tape recording of the noise and played it to the current Porsche dealer who is trying to help he tells me unless a technician can witness the noise they are not willing to conduct a deeper investigation. I would be very grateful if anyone on the site has experienced an issue like this and if/how it was resolved would get in touch and share their experience. thank you David Wood Ross

DAVIDWOODROSS said: I bought a 911 in October 2021 from a main Porsche dealer. A few weeks after purchase I could hear a high pitch screeching noise seemingly emanating from the PCM screen but it quickly disappeared. Since then the noise remains but only heard on an intermittantl basis, i.e weeks can pass without hearing it. The noise has a mind of its own but it only starts when I reach 49mph and continues in higher speeds. It can be heard with the soundsystem on or off. The vehicle is still under warranty and I have taken the car to the dealer I bought the car from and another Porsche dealer who is closer to where I live. However, after testing neither could not hear the noise. Although I made a tape recording of the noise and played it to the current Porsche dealer who is trying to help he tells me unless a technician can witness the noise they are not willing to conduct a deeper investigation. I would be very grateful if anyone on the site has experienced an issue like this and if/how it was resolved would get in touch and share their experience. thank you David Wood Ross This happened to me when I had my windscreen changed. The plastic strip covering the gap between pillars and the screen was not seated properly on the outside of the car causing it to make a high pitched whistle which changed pitch with speed.

Thank you so much for responding so quickly. The situation is driving me insane. The local Porsche rep asked me to maintain a diary and every time I take the car out record key data i.e time/speed etc, I have now complied on a daily basis for the past 7 days but each time I the noise has refused to cooperate. Your experience with your windscreen - I assume you heard the noise internally coming from the PCM area? Is that right and how was the issue resolved? Pleased to hear from you

I would say if you bought a 100k car , they should be doing all the leg work and you shouldn’t be having to keep a diary for them

Thanks for your response. My car is a 63 plate so not £100k. However, your remarks are valid but the limtations of a Porsche Warranty i.e apparently Porsche dealers are not reimbursed for diagnostic costs so they have no incentive to do a comprehensive fault finding exercise. In my case they have insisted they must hear the noise before carrying out any further work although they have heard my tape. Therefore, I find myself in a 'double bind' its been more than a week since I last heard the noise (that does not mean it has disappeared) and since I am unable to record it, Porsche will not continue further investigations.

My noise emanated throughout the car. The only reason I knew it was the windscreen was because it had just been changed. If I had just heard the noise without that information Id have had no clue. In regards to PCM noise, in other cars, particularly older stuff I found when i had this type of noise coming from the audio system it changed pitch with revs and turned out to be a bad earth on the audio unit or amp. What i would do is ask them to temporarily remove the unit for a week or so and see if it goes. If it does then you know its the audio system or peripheral wiring. The other option is to go and see an audio specialist who can check the wiring, but being on a Fibre CAN Bus it maybe difficult to diagnose. Thats where my knowledge ends Im afraid. Hope that helps.

Many thanks again for your message. I told the Porsche dealer before that since the noise seems to be originating from the PCM the fault could be the amp but my suggestion was dismissed. I will return to the dealer and ask them to carry another investigation along the lines you have suggested. If they refuse I will look into your alternative suggestion.

Please keep us updated. Good luck.

I am still trying to find a resolution to the noise defect issue but not making much progress. What I have discovered is my research has thrown up a massive can of worms regarding the Porsche Approved Warranty bringing Consumer Law (mis-selling) and Porsche brand reputation into play. I am awaiting a response to my last email to the selling dealership and will revert. David Wood Ross

DAVIDWOODROSS said: I am still trying to find a resolution to the noise defect issue but not making much progress. What I have discovered is my research has thrown up a massive can of worms regarding the Porsche Approved Warranty bringing Consumer Law (mis-selling) and Porsche brand reputation into play. I am awaiting a response to my last email to the selling dealership and will revert. David Wood Ross Oh really, sounds ominous.

Have you had a good explore with the HVAC settings OP? It's all right behind the PCM, you might find that it's a blower motor or flap actuator or just something caught in the ducting. It could be that if you have it set on Auto it's only hitting the sweet spot every now and again and could even seem weather dependent. If you have a go at a combination of manual settings that cover fan low/medium/high, hot/cold/inbetween, up/face/down, recirc or AC on and off and engine hot and cold you might be able to provoke it

for The Wookie Many thanks for your suggestion which makes a lot of plausible sense. I will now test following your guidance and let you know the result. I took the car to two Porsche dealerships in recent months for investigation and because they could not hear the noise will not carry out any further diagnosis. They say it is an acoustic problem not covered by the Warranty because it does not affect functionality. What bull....! and what about my enjoyment which is what driving a high performance Porsche is all about?. My lawyer will love to get his teeth into this but I am not at that stage yet. thanks again David

Wookie, Thanks again for your help and tested my car on two occasions over the weekend along the lines you suggested but disappointingly was unable to replicate the noise. Nevertheless I still think your theory has potential merit and will explore further with Porsche, if I can convince them to investigate further. As mentioned in a recent post Porsche are being difficult regarding the Porsche Approved Warranty which I may have been mis-sold and may also have brand reputational implications. I am finding the topic shrouded in mystery and non disclosure since many Porsche employees I have spoken to have not been forthcoming in providing information. I now know why and was shocked to learn for the first time recently that all Porsche employees have to be FCA qualified before they can sell these Warranties and discuss their T's and C's with a customer. The plot thickens since I also have discovered the Warranty is in fact not a Warranty but an insurance policy (a big difference between the two) outsourced to a third party insurer. In my case, I only became aware of this when I realised I never received a Warranty certificate which should have been given after I bought the policy. A week ago, after requesting I was emailed the document certificate which confirmed it is an insurance policy and provided the name of the insurer who underwrites the contract. I would much appreciate hearing from any forum member who has purchased such a Warranty to get in touch and confirm or otherwise if they knew about any of these facts prior to buying the Warranty. Thank you. David

For Wookie I have continued testing and on 5 April had a breakthrough when after setting the HVAC at 22 C and Auto off the noise began after leaving my home and continued for an hour at speeds of 15 and 60 mph. It has not behaved like that before. However, after switching the engine off for 10 minutes I drove again for 15 minutes (same settings) but the noise was not heard. I stopped and tested again 5 mins after.and the noise returned. The next day tested for 5 times and the noise was heard twice. I was able to record each time. Next week I will return to Porsche locally with this new information and hope they will do something. However, I am not optimistic! It would help my cause if you were able to expand your knowledge when you said it might be a blower motor or flap actuator or something in the ducting. Have you had experience with these issues? I am talking to Porsche from a position of relative ignorance so with more technical information might convince them to investigate. Because their software says NO they are not taking my issue seriously enough despite hearing the first recording of it. I have reported the matter to Porsche GB who are a wholly owned subsidiary of Porsche AG but they are equally unhelpful. Any extra information you have can only assist my campaign. Many thanks again David Wood Ross

Sorry no specific experience beyond knowing sort of how these systems generally work and where they are in the car. Sounds like you’re getting close to making it repeatable though! Try and think about anything else that might coincide with the behaviour eg weather conditions, time of day, fuel level, have you just done a long journey (so battery charge or residual temperature) even random stuff like whether it’s parked uphill or downhill If you can’t get it 100% repeatable then the best thing you could do is get it to happen and drive it straight to the dealer workshop and let them hear it. As soon as they’ve heard it then it’s ultimately their problem.

Thanks again Wookie for the suggestions. I have been keeping a diary since 22 February - 7 April less two weeks off with covid) and logged 25 tests noting time/weather/speeds/ roof open shut/auto on of/ air temp/ moved temp control in cabin/ etc and heard the sound 10 times. So no of test days excl covid 31. Monthly sound result: Feb (6 days) 0 times March (4 days) 4 times April ( 5 days) 4 times. You mention fuel level which is interesting which I never paid much attention to before. I heard the noise 4 times over 5/6 April but since late pm 6 April when I topped up to 3/4 full, after short testing 4 times yesterday the sound was not there. However there may a correlation since the fuel level was very low before filling. However, when I last filled up with low fuel pre covid the noise was not heard. Nevertheless, there could be a link with extra weight or its distribution. Having said that the car feels more solid when driving after filling up but may be my imagination. Who knows? but will continue testing today and over Easter. Nearly forgot to say during both last tests the noise began at a speed of around 15 mph whereas previously it would only start at 49 mph. Maybe significant? You also suggest taking it to the dealer workshop. Just to demonstrate how difficult and temperamental the noise is. I mentioned the local Porsche dealer is only 5 miles away and on two occasions I heard the noise I changed course and headed for the dealer and the sound accompanied me. On both occasions I managed to get a technician to immediately escort me on a test drive and guess what? sods law came into play and the noise was not evident. Porsche are insisting they witness the noise before they do any diagnostic work. Any further insights would be most welcome. Thank you again

No probs! Fuel level I was actually thinking fuel pump as the tank is ahead of the bulkhead and any noise could sound like it’s coming from where you’re describing. I’ve experienced a pump on the way out whirring intermittently on a low fuel level, although it wasn’t a Porsche most modern cars are all similar In terms of going to the dealer, I mean actually phone them on your way and get the technician to come out while you’ve kept it running.

Wookie, Thanks once more. I had not thought about a possible failing pump and its location but was thinking the extra weight after a refill could in some way shift the wiring or unknown parts which are causing the noise. Will mention this to the local dealer when I go there this week. Your suggestion phoning whilst on my way and getting a technician iwho would be available at short notice to come out for a test.whilst I wait and keep the car running is unlikely. I have known this dealership for 20 years and I now feel they are getting fed up with me bothering them unless I agree to pay for an investigation which could be akin to offering them a blank cheque. I will ask and let you know the result after my meeting with them.

Wookie, Here is the latest.I have been keeping a log and driving test record since 22 February. I did this at the suggestion of the service adviser at the local dealer and wrote up my findings although I didn't discover anything which linked to a cause. Last Monday I called the guy and asked if I could meet to discuss my report and informed him I recorded the noise (now very loud) 3 times over the weekend which I e-mailed to him. He acknowledged 'WHAT A NOISE'. but repeated what he told me before a noise defect is not covered by the warranty if it doesn't impact funtionality. He also he repeated what he has said many times 'somebody in the dealership has to witness it before we can act' He offered no explanation when I countered and asked 'is driving not a function?' particularly when it overides hearing the radio/CD, impacts my concentration and distracts my attention which is a safety matter. His answer he did not write the policy. Another copout!! I then also asked for a meeting with the dealer principal which triggered a response and whilst he turned down a meeting he asked me to bring the car in again for 2 days on 20/21 April. You may appreciate my position so we'll see what develops but given the obstacles Porsche are putting in the way I cannot envisage a good outcome. After reading reviews on Trust pilot about Porsche GB and Porsche generally whose service ratings are pretty awful eroding my confidence even further,however, it will come as no surprise to me to learn they get good ratings about Porsche sales people particularly when they are selling brand new cars. A month ago I made a complaint about this and other issues to Porsche GB (a wholly owner sub of Porsche AG) and accused the brand of mis-selling the warranty, which is a reputational issue for Porsche. They failed to take me seriously so I e-mailed the just appointed CEO who referred me back to another w....r in their service dept who called me 2 days ago but guess what? knew nothing about Warranties. He is now going to refer things to his legal/warranty dept for an opinion. Make it up? You couldn't! Matters are further complicated since I have decided to sell the car. If the defect is not resolved can you imagine how difficult this could be? Apologies for the rant but trust you and others reading about my experience may be interested and find it beneficial in any future dealings they have with Porsche. David Wood Ross David Wood Ross

TO: Wookie and everyone who has contributed Update since my last. The local Porsche dealer asked me to bring my car in for further investigation. After 5 days in this dealership they conducted 4 tests and heard only one noise which was recorded and attributed to a faulty rear seat buckle. However this noise has no correlation to my recording. Nevertheless they have ordered a replacement buckle which arrives in 3 weeks. Clutching at straws! Its a computer says NO situation since if Porsche software cannot detect a fault then Porsche junior technicians do not have sufficient experience or out of the box thinking to find a solution. The only way forward is to find a Porsche technician somewhere in the network who has some acoustic fault finding experience. A response from mumsn3t on 2 March suggested an audio specialist which now seems a good idea but after trying on the internet I have not found anyone with the necessary skills. In my mind my car has become tainted so I need to get rid but selling with a noise? Imagine what this could do to its value!!! . Appreciate any suggestions from readers. David Wood Ross

Does the noise continue of you turn the AC off? When the ac gas drops below the correct level it will start to make a whine/whistle noise. The noise will change depending on the temp you set and the fan speed etc. But force the AC off when you next hear the sound and see if it stops. Or just get your climate checked, but get it checked with a proper AC guy, not some kwikfit type place as the levels need to be very precise on these. It might not be anything to do with that, but it is the first thing I check with whine/whistle sounds for the cabin.

For deutsche.dianostics Many thanks for your message. Both condensers were replaced a few months ago. Your suggestion may have merit. The noise is mostly heard when the A/C is off. I took the car into the local OPC and they kept it for 5 days, tested the car 4 times, heard 'a' noise once and recorded it and concluded the fault is due to a noise from the rear seat buckle. After listening ,this noise has no correlation with the actual noise which emanates from the dash (around the PCM area). Anyway the OPC has ordered a new buckle which will be delivered in a few weeks. You suggested get the climate checked with an A/C guy. Can you please explain a little more? many thanks David

can you not upload the noise somewhere so ppl can listen to it?

DAVIDWOODROSS said: The noise is mostly heard when the A/C is off. You suggested get the climate checked with an A/C guy. Can you please explain a little more? many thanks David If the noise is heard when the climate is off, it won't be low gas. I said to get the levels checked with an AC guy as they will get the levels absolutely bang on, unlike some of the kwikfit type places that have a range. But if you have pressed the A/C button, and the light is off, and it is still making the noise it should not be the system. Also, turn the fan speed down until the display says "off", just to make sure.

I had a high pitchsd noise on my car, it was a faulty rca connector (amp lead) on the Bose. It took me months to find it and it did it with stereo completely off.

for Duetsche/Wyson/Caddyshack. Thanks fo the suggestions. I have not heard the noise since 26 April when I collected the car from the Porsche dealership. The noise is not cooperating by letting me hear it. As I said it is intermittant, it can be days until I next hear it. Therefore the timing of the noise makes it more difficult to involve an A/C specialist who could wait for day to hear it. Anyway this week I will make enquiries with A/C companies who offer diagnostic services. Caddyshack mentioned a faulty rca connector linked to the Bose. Did you diagnose or someone else? Wyson - sorry but can you tell me what a ppl is? Both OPC's have a recording of the noise but have not come up with any suggestions. Really appreciate your help DWR

I noticed that the sound seemed to come from near the door speaker so I took out the stereo and fiddled with all the wires until the sound came and went. I then spoke to a stereo shop who knew porkers well and they said it was quite common.

DAVIDWOODROSS said: for Duetsche/Wyson/Caddyshack. Thanks fo the suggestions. I have not heard the noise since 26 April when I collected the car from the Porsche dealership. The noise is not cooperating by letting me hear it. As I said it is intermittant, it can be days until I next hear it. Therefore the timing of the noise makes it more difficult to involve an A/C specialist who could wait for day to hear it. Anyway this week I will make enquiries with A/C companies who offer diagnostic services. Don't make enquires yet, just wait till you hear the noise again, and then hit the AC button. If it stops when the compressor kicks off it is that, if not, the search continues. One other thing to check, the cabin filters. Just make sure they are in properly, and that the covers are on properly too. These can make a whistling noise if gaps.

Sorry about the text speak, ppl = people. If you upload the recording online, you can get more opinions, someone here might have had the problem before. Not on a Porsche, but I’ve had ‘high pitched noises’ before: 1) windscreen trim that was loose. (whistling, dependent on speed) 2) failing fuel pump. (whining, dependent on fuel level) 3) feedback from an aux port. My phone connected to a 3.5mm jack, connected to a cigarette lighter charger would playback a high pitched sound from the speakers that rose and fell with revs, I needed to get a ground loop isolator fitted. (buzzing, dependent on if the phone was charging or not) All of these were high pitched intermittent noises but different. Listening to a recording will definitely eliminate some potential sources. You mentioned a tape recorder, but any smartphone will have a recording feature and easily enable you to upload it somewhere. Edited by anonymous-user on Tuesday 2nd May 12:44

Thanks again for all your suggestions. Just back from another test and was pleased to hear the noise is playing ball today. I started the test at 15.50 hours and ended 30 mins later. Unusually (usually 49 mph +) it started about 25 mph and continued for the duration. As deutsche suggested I adjusted the A/C settings. Temperature set at 22c with A/C off and then on, the noise could be heard on both. Interestingly, when I increased the blower speed to max I could still hear the noise on A/C off but when on, the noise just about disappeared. Deutsche ? appreciate your thoughts do you think A/C related? You mention cabin filters how do I check those? I have a number of recordings on my iphone but not able to upload on this site, it seems only images accepted?? Can anyone help? Look forward to more suggestions thank you all

I don't know to be honest. Did you adjust the temperature too? If so did the noise change? Just search google for "changing cabin filters on Porsche 991". However, if the noise starts at speed, 49mph+, does it stop when you slow from that speed too? We are getting into tyres, bearings, diff, gearbox if so. Or something as simple as some trim is loose and whistling at speed.

You can upload your audio files at https://audio.com and then you will get a link to share it which you can paste here for us to listen to. Next time the noise appears, record it on your phone and move the phone around the cabin, from corner to corner, up, down, footwells, each speaker, and in each location you move the phone to, say where the phone is. The recording will be loudest when the phone is closest to the source of the sound, and that might give a clue where it's coming from. I have a 63-plate Porsche 981 (Boxster S with 3.4L engine, so essentially the same engine as yours) that used to make a high-pitched squealing noise under maximum acceleration. It turned out to be the accessory belt. The noise never lasted for more than a couple of seconds on mine, but a looser belt might slip and squeal more. Perhaps your accessory belt needs to be replaced? It's a long shot, but thought I'd mention it.

thanks again to all. Questions: temperature no adjustment just maintain at 22c. Speed at 42mph and slowing down yes it does stop. TRim remains a possibility but not I think windscreen which jus checked again and the external seals appear to be tight.A loose trim perhaps. I will check cabin filters. Lunar one: record at different positions around the cabin. Will try that when I get my wife to accompany me. reverting

Coming to this late, so apologies. What an annoying fault. Are you sure the issue is speed related not just revs? If not already tried, with engine warm and car static, raise revs to 3, then 4K and see what happens. I realise that since its intermittent no noise won't prove anything but keep trying. IF you can eliminate revs alone as the issue, the cause must be movement of air, which starts to narrow things down. Equally if revs when static still cause the noise, it's probably an electrical problem, or maybe an a/c fan blade running out of true.

Many thanks again for all your advice. Here is a quick update. Firstly, have not got around yet to try and upload a recording but I will get to it soon. Removed and check air filter under bonnet and did not appear very dirty but vacuumed and replaced. Will attempt to do the same with the under glove box filter but which is more difficult. Sib's suggestion will try today. The local clutching at straws OPC gave me a recording of rear seat belt noise they think is the cause and listened. It bears no correlation to my recording. Also on my to do list as was suggested earlier I have been trying to find an acoustic engineer with experience in transport acoustics but so far that is proving pretty difficult. My wife and I over the weekend (I had to give the Coronation a miss) have been searching the internet extensively and she found a Porsche owner back in 2017 who had similar problems with his noisy A/C i.e. whining noise coming from the dash right behind the a/c controls which gets louder as engine speed rises. I have had difficulty with the a/c pre replacement condensers but now thinking it is a/c related. Also discovered that 991 models have some history of a/c issues. The noise itself is behaving and is allowing me to hear it almost on a daily basis. I am going out now for another test. laters DWR

If you have had the condensers replaced recently who filled your climate up? I have found none of the big places like Halfords, Kwikfit etc. can get the levels right on any 996 or 997 and always use a climate specialist. Those cars are very fussy about the levels and when slightly low they do make a horrible sound that sounds like alternator whine like you get on a badly fitted stereo system. BMWs are the same, so expect the 991 to be no different. It may not be anything to do with that, but just thinking out loud. However, drive it around, adjust the air con on and off and adjust the temperature and if the noise changes as you do it, then that is what it is. If it doesn't change then more detective work needed. I would pull the fuse for the stereo system too. It might be a bad earth going to the amp? In fact, pull the amp connector out, clean it up a bit and put it back in. Once it starts to make the noise does it then continue until you turn the car off?

Just back from another test to see Deutsche has replied to my last. but first sib's suggestion re: revs v speed tested to 3-4k revs while static and did not hear the noise. Interesting test this time: 5 mins after engine warmed up left for local shop and noise came on at 28mph ( settings as normal 22c,sound system off and a/c on). After shopping changed settings to LOW temp and fan to max, cabin very cold and drove to the nearby by pass and increased speed to 80mph. Did not hear the noise at all! but switching back to previous settings the noise was also silent. Confused? I am! This action would suggest it is a/c related but what do I know? Deutsche what do you mean by climate and levels? Refrigerant perhaps? Your question: yes the noise contines until I drop speed now below 28mph and when I turn the engine off. Look forward to hearing thanks DWR

You really need to start playing with the temp etc. when you hear the issue, not after you have stopped and start again. Adjust the temp and see if the noise changes. Ideally when sat doing 60mph or whatever. When I say levels I mean the AC refrigerant level in the system.

Many thanks for your last Deutsche. Before I took the car out for test, thinking of my historical experience of the noise which behaves like a spoiled temperamental child and takes offence easily which probably meant it was upset with my tinkering yesterday. My gut told me it would not make a sound and having just got back from testing it did just that. Anyway, and although the noise was absent I took your advice and went thru a range of the temp settings, air con off/on, fan at max/min but no sound. I will trepeat again when the noise returns but may have a few days to wait. Meantime I have been doing more research on various technical sites about the 991 series in the UK and the US and it seems there are many examples of owners experiencing noise issues which are A/C related. The causes range from compressers, condensers,re-gas, refrigerant levels, leaking pipes, drive pulleys, expansion valves and a big contributor it seems are radiator fans, etc, etc. Take your pick but I am coming to the view that all the clues point to an A/C problem. Do you agree? I do not have the technical know how to understand how all these components work with a system and operate in harmony but one thing is certain the moise is coming from behind the dash to the left of thye PCM where I assume some of these parts are located. these parts are located in the vehicle. Therefore, I have to find a Porsche specialist technician who has the skills, experience of A/C systems. Someone who can think 'out of the box' but where? most probably lurking within an independent Porsche workshop. Over recent years, many of the skilled and experienced Porsche mechanics have been poached by independent competitors in the UK anyway leaving the young and inexperienced techies in the OPC's. Just a thought! If you agree the a/c is the likely cause I will put pressure on the local OPC to do a proper investigation after convincing me they have the necessary skills to find a solution. Look forward to your opinion and thanks again.

Deutsche, I took the car out this morning for more testing and the noise returned after 10 minutes on the road.starting at 30mph. I tried your suggestion whilst the noise was heard and changed the temp settings thru the range from LO to HI and the noise remained. However, when I turned the booster fan (as mentioned previously) to max on each of the temp settings the noise disappeared. I also heard the noise has slightly changed its pitch to a chirping (birdsong) sound. You mentioned this in your first post as being refrigerant related? Also another new development! It is a warm day here and after opening the sunroof the noise stopped but as soon as I closed it the sound reappeared. A/C and air related perhaps? any thoughts?

DAVIDWOODROSS said: Deutsche, I took the car out this morning for more testing and the noise returned after 10 minutes on the road.starting at 30mph. I tried your suggestion whilst the noise was heard and changed the temp settings thru the range from LO to HI and the noise remained. However, when I turned the booster fan (as mentioned previously) to max on each of the temp settings the noise disappeared. I also heard the noise has slightly changed its pitch to a chirping (birdsong) sound. You mentioned this in your first post as being refrigerant related? Also another new development! It is a warm day here and after opening the sunroof the noise stopped but as soon as I closed it the sound reappeared. A/C and air related perhaps? any thoughts? Sounds very much like the blower motor to me - specifically the bearings. The motor loading will be very different depending on whether the roof is up or down. And it will also depend on the commanded speed from the HVAC system.

DAVIDWOODROSS said: Deutsche, I took the car out this morning for more testing and the noise returned after 10 minutes on the road.starting at 30mph. I tried your suggestion whilst the noise was heard and changed the temp settings thru the range from LO to HI and the noise remained. However, when I turned the booster fan (as mentioned previously) to max on each of the temp settings the noise disappeared. I also heard the noise has slightly changed its pitch to a chirping (birdsong) sound. You mentioned this in your first post as being refrigerant related? Also another new development! It is a warm day here and after opening the sunroof the noise stopped but as soon as I closed it the sound reappeared. A/C and air related perhaps? any thoughts? Have you checked the AC refrigerant level..? I’ve had peculiar noises from a 996 HVAC system when the AC gas level was low. I still had adequate cooling performance, but it was occasionally noisy. I believe the only way to check it is to fully evacuate the gas and measure it, then refill with the correct volume.

Definitely get a local air con specialist to pop over and get the levels set correctly. When the climate starts to make that noise, due to levels being incorrect, cracking a window slightly used to get rid of the noise. I'm still not saying it is this. But for £60-70 for someone to come to your house, drain the system and put it back so you have exactly the correct levels of refrigerant and oil in there, why not try? Even if it doesn't sort the issue, you will know your climate should be good for another few years, or until you get a leak on the return pipe seal or a hold in the condensers.

Thanks Deutsche, Lunar One and IREvans for your contributions which gratefully received. The local OPC continues to stand by its original position and will not conduct any robust diagnosis because of the Warranty exclusion re acoustics. Meantime I have arranged to take the car in to a Porsche indy workshop on 1 June who assure me they will find a solution.Before that I will today try and find an a/c specialist to come and look at the refrigerant, blower fan, etc. reverting

DAVIDWOODROSS said: Thanks Deutsche, Lunar One and IREvans for your contributions which gratefully received. The local OPC continues to stand by its original position and will not conduct any robust diagnosis because of the Warranty exclusion re acoustics. Meantime I have arranged to take the car in to a Porsche indy workshop on 1 June who assure me they will find a solution.Before that I will today try and find an a/c specialist to come and look at the refrigerant, blower fan, etc. reverting Just take the car to an AC specialist. You’ll have the refrigerant evacuated and refilled with the correct quantity in no time and for a reasonable cost.

Late to this; but remember reading it a while back. The sunroof/AC could be the link - the AC and sunroof both have drains that exit the car from inside. The AC also has a flap that blocks inside from outside (recirculation flap) in the passenger footwell. Any chance it could be a wind noise generated by a small gap around a seal or literally air pressure down a drain hose? Open the sunroof and temporarily tape over the drain holes in the corners at the front (masking tape) and drive it to see if it changes anything. Put the climate control on recirc mode and have a poke around under the passenger side dash area - the recirc flap is foam covered and can distort, allowing air past when a differential exists between inside/outside the air box. If you hear the noise; if you tap a window down a few mm does the noise stop?

Many thanks Pope. Before commenting, a few people have suggested I take the car to a specialist A/C firm and drain/replace the refrigerant. I googled this and found only 3 specialist firms in the South East (none locally) each long distances from me. I contacted each who asked me to bring the car in. The logistics make this not practical. Meantime, a new development. A few weeks ago I e-mailed Porsche AG, they did not answer but sent my message to Porsche GB who contacted me and offered to pay for a 2 day investigation. Last Wednesday I returned the car to the local OPC but to date the noise has not been heard but will continue testing. Pope may have identied a possible cause. I will ask the OPC to check on their return tomorrow and revert. thanks to all again

DAVIDWOODROSS said: Many thanks Pope. Before commenting, a few people have suggested I take the car to a specialist A/C firm and drain/replace the refrigerant. I googled this and found only 3 specialist firms in the South East (none locally) each long distances from me. I contacted each who asked me to bring the car in. The logistics make this not practical. Meantime, a new development. A few weeks ago I e-mailed Porsche AG, they did not answer but sent my message to Porsche GB who contacted me and offered to pay for a 2 day investigation. Last Wednesday I returned the car to the local OPC but to date the noise has not been heard but will continue testing. Pope may have identied a possible cause. I will ask the OPC to check on their return tomorrow and revert. thanks to all again Of course they are going to need the car to check and refill the refrigerant, they need to connect specialist equipment to the car to evacuate and then refill the system. It won’t take long, no more than an hour.

After 7 days in the local OPC workshop, I am very pleased to report at long last the cause of the noise has been identified by a senior technician. It is due to a faulty passenger door window dropping very slightly (not visable from a seated position) from a closed position allowing air into the cabin thus creating the high pitched sound which transfers to the dash thus creating the misleading illusion of its source. Once heard, the sound is easlily stopped by moving the door switch to the closed position. After 3 days testing I returned the car to the local OPC this morning where they replaced the faulty door switch. Difficult to believe I know but since living with this problem for 18 months or so, there have been many false dawns. My sincere thanks to everyone on this site who assisted by offering ideas as to the potential cause and contributed to the debate. I am very grateful. DWR

DAVIDWOODROSS said: After 7 days in the local OPC workshop, I am very pleased to report at long last the cause of the noise has been identified by a senior technician. It is due to a faulty passenger door window dropping very slightly (not visable from a seated position) from a closed position allowing air into the cabin thus creating the high pitched sound which transfers to the dash thus creating the misleading illusion of its source. Once heard, the sound is easlily stopped by moving the door switch to the closed position. After 3 days testing I returned the car to the local OPC this morning where they replaced the faulty door switch. Difficult to believe I know but since living with this problem for 18 months or so, there have been many false dawns. My sincere thanks to everyone on this site who assisted by offering ideas as to the potential cause and contributed to the debate. I am very grateful. DWR If it's any consolation, the window switches on these cars are notorious for going bad. I had a dead window switch on my first 981 Boxster S, and due to the lack of a rain gutter, they get dripped on frequently when you need to open the window. The switch on my second car was starting to do the same thing but now that it's warmer, the symptoms have disappeared. Symptoms are windows moving by themselves, or refusing to move as commanded from the switch. Or not moving as required when opening and closing the roof. I imagine I'll need to replace the switch. It ought to be easy, but the design of the switch retainer means you have to take the door card off to do it which is very annoying. See my thread here if you're interested: https://www.pistonheads.com/gassing/topic.asp?h=0&...

DAVIDWOODROSS said: After 7 days in the local OPC workshop, I am very pleased to report at long last the cause of the noise has been identified by a senior technician. It is due to a faulty passenger door window dropping very slightly (not visable from a seated position) from a closed position allowing air into the cabin thus creating the high pitched sound which transfers to the dash thus creating the misleading illusion of its source. Once heard, the sound is easlily stopped by moving the door switch to the closed position. After 3 days testing I returned the car to the local OPC this morning where they replaced the faulty door switch. Difficult to believe I know but since living with this problem for 18 months or so, there have been many false dawns. My sincere thanks to everyone on this site who assisted by offering ideas as to the potential cause and contributed to the debate. I am very grateful. DWR Finally, a solution…! So glad you got it sorted…

Nice one! Always nice when someone actually reports back on the remedy as well.

Not being funny but pressing the window up button to ck it’s up would have been the first thing I would ( and many others I suspect) would have done . Basic stuff ……..from the Op and more so the techs .

Fiammetta said: Not being funny but pressing the window up button to ck it’s up would have been the first thing I would ( and many others I suspect) would have done . Basic stuff ……..from the Op and more so the techs . Captain hindsight has arrived…!

fiametta Thanks for you message! Sorry but I cannot help but respond Funny eh? I can tell you have a sense of humour but you are a bit late to the party, if only you had applied your superior knowledge after first posted best DWR

DAVIDWOODROSS said: fiametta Thanks for you message! Sorry but I cannot help but respond Funny eh? I can tell you have a sense of humour but you are a bit late to the party, if only you had applied your superior knowledge after first posted best DWR

Tagteam said: I would say if you bought a 100k car , they should be doing all the leg work and you shouldn’t be having to keep a diary for them Can't fault your logic there but I can only suggest you have never dealt with an OPC.

DAVIDWOODROSS said: fiametta Thanks for you message! Sorry but I cannot help but respond Funny eh? I can tell you have a sense of humour but you are a bit late to the party, if only you had applied your superior knowledge after first posted best DWR I am very late to this apologies. Every “window drop “:coup or cab I have had , talking Ferrari ,Bentley and pork has had the odd minor glitch with the “;drop “ leading to “;whistle “:Usually associated with low battery issues or new battery issues . There are well recognised re set protocols in the handbooks . Obviously tap them up as a short term immediately effective measure while driving .