Noisy air conditioning - are they all like this?

[Rory]

As I get used to car I've become aware that when the a/c is on there's a kind of strangulated  / straining fan noise coming from the behind the dash, that is very obvious when the car is at idle.

 

It's not the blower fan - the noise in unrelated to blower fan speed - and it stops and starts immediately the a/c button is pressed.

 

It's not the engine cooling fan either - I know that starts and stops with the a/c but it's barely audible even under the bonnet, and anyway the noise is instant when the a/c button is pressed and the cooling fan takes a while to spin and (especially) down.

 

Obviously the TSi engine is quieter than our diesel was, but, with the radio off, this noise is quite dominant in the cabin when the car is stopped at junctions etc.

 

Are they all like this?

 

Edited 18 August, 2023 by Rory

[CJJE]

I've not noticed this myself... a daft question perhaps, but are the dashboard vents open?

 

Chris

[Rory]

The vents are open but it's not the blower fan - you can wind that up and down and the noise is separate.  Once the blower fan is a few steps up it drowns out this other noise.

[J.R.]

Try switching between recirc and fresh air, mine is noisy on one of them (cant recall which) when the pollen filter is clogged which is most of the time!

[SurreyJohn]

Try turning temperature to low, then after about 20 seconds to max, then after another 20 seconds try manually switching to feet, then to screen etc.

 

Basic idea is if there is a sticky motorised flap in the vent, by manually forcing all the possible combinations and allowing time for flap to fully move you clear whatever the problem was.   Might work (or might not)

 

 

[Rory]

Thanks for suggestions.

 

It doesn't seem in any way related to the blower fan or flap positions or recirc.

 

The odd thing is that the noise stops and starts instantly when the a/c button is pressed on and off.  If it was low gas causing the system to be noisy I'd expect there'd be something of a delay.  I wondered if it was "air care" related but it doesn't make any difference if that's on or off.

 

My wife (it's her car, really) 'reported' it to me and it's really not like her to notice car stuff!  I dismissed it at first but once you tune in to the the noise it's really quite obvious.

 

[J.R.]

1 hour ago, Rory said:

The odd thing is that the noise stops and starts instantly when the a/c button is pressed on and off.  If it was low gas causing the system to be noisy I'd expect there'd be something of a delay. 

 

No delay, low refrigerant can cause a whistling noise from the metered orifice where the gas expands in the evaporator.

[Routemaster1461]

I had a car, different marque, which had a slow aircon leak that was never solved in the 6 years I had it. I always new it was on its way out due to the whistling noise from behind the dash.

[croquemonsieur]

I started to notice a sort of  whirring noise coming from the front a month or 2 ago on a MY19 Karoq SE Tech.  I only just got round to reading this thread this morning and so on a short journey today, can confirn that mine does similar -  turn aircon off and noise goes instantly.  However, on mine I seem to recall the noise dissappears when I'm idling and does not happen for a while when starting from cold - I'll check & report back further on these last 2 events and also try some of the other proceeduress noted above.  I should note that the 1.0 DSG petrol engine is very quiet, but I wasn't aware of any such noise until recently and would be nice to get rid of it.

 

I wonder how easy it is to get at the pollen filter.  It should have been cleaned or is it replaced at a 4yr service one month ago.  Garage is normally pretty good from what I can tell.

[Rory]

Thanks for that.

 

Our car hasn't been used much since we got it.  I was prompted to start this thread after a 40 mile round trip (that's a long trip for my wife!) last week and it was really pretty noisy.  She had mentioned it before but, to be honest, I'd just shrugged and dismissed it, thinking it was just because the car is different, and, as you say, the engine is quiet so far all I know the diesel Tiguan we had could have been the same!   

 

I started the car over the weekend and ran it at idle for a bit and there's a trace of a noise coming and going, but nothing like as noticeable.  So perhaps the system needs to be run for a while before it beomes more noticeable.

 

I've pinged the dealer an email anyway.  I'm thinking it might need regassing and I don't want to pay for that having only had the car a couple of weeks.

 

The pollen filter is behind the glove box - bit fiddly to drop the glove box down.  Pollen filter is supposed to be changed every 2yrs.

Edited 22 August, 2023 by Rory

[Apprentice]

"I wonder how easy it is to get at the pollen filter."

 

 

A bit fiddly the first time I guess.

[irfant]

A whistling noise was coming when the AC was ON. The AC compressor was changed under warranty due to faulty nozzles

 

That is all I can say in my case

[Rory]

I just took the car out for a run around our village and the noise - I think heavy whirring is better than my initial description - is certainly still there.  I also noticed that it's engine speed dependant, getting louder between idle and maybe 2500RPM - it's as if there's something horrible going on in the DSG, but the noise stops instantly when the a/c button is pressed.  And starts instantly too. 

 

It's just as if there's an additional a/c specific blower in the dash, but I'm not aware that's the case.

[xman]

Its probably low on refrigerant but as its a 2022 model, only one year old you should take it in to a Skoda dealer and complain and get it sorted under warranty.

 

Maybe has a leak in the a/c or worst case, a failing compressor.

 

Edited 23 August, 2023 by xman

[Sanqhar]

If the noise is only when the aircon is on then it is most likely the compressor or the compressor clutch.  The compressor via its clutch is only activated when the aircon is on.  Try listening for it with the bonnet open and someone else is switching the aircon on and off.

tom

[xman]

Its a variable displacement compressor and so doesn't have a clutch.

 

So its either low on gas or oil.

 

Note that even a perfect a/c is not totally noise free, so depends on what you class as noisy.

[croquemonsieur]

In the last 2 days I haven't noticed the air-con noise so much but I havve had other things on my mind.  I'm actually wondering whether the noise followed on from a period of time when the air con was switched off - only noticed in that recent hot June month.  I believe it is best for the air-con system if it is kept on all the time and don't know how long mine had been off - could have been many months - must have been knocked sometime or other.  I might get an air-con specialist to look at it sometime.

 

Anyway I'll continue to monitor the situations when the noise is or isn't there and report back later.  Thanks for the YouTube link on replacing the pollen filter, Apprentice.

[Routemaster1461]

It is not neessary to keep aircon on ll of the time. All you need do is to use it for a few minutes about once a month

[J.R.]

3 hours ago, croquemonsieur said:

I believe it is best for the air-con system if it is kept on all the time and don't know how long mine had been off

An urban myth inasmuch as your system with the variable displacement compressor is concerned.

 

As you say the noise follows engine speed and sounds like the DSG box going wrong can we be sceptical about the noise coming from the dashboard area? After all the DSG box is not located there.

 

A partially separated shear plate or pulley bearing would explain the noise now that you have added more info, I suggest you open the bonnet and listen for the noise there when the engine is running, get an assistant to switch the AC on and off and run through the rev range with it in both states.

[J.R.]

2 hours ago, Routemaster1461 said:

It is not necessary to keep aircon on ll of the time. All you need do is to use it for a few minutes about once a month

 

Further diffusion of the urban myth, the compressor pumps a small quantity of refrigerant around the system even when switched off.

[Rory]

5 hours ago, J.R. said:

 

Further diffusion of the urban myth, the compressor pumps a small quantity of refrigerant around the system even when switched off.

 

I wonder what percentage they go down to?  I used to have a Merc (also with a swash plate compressor) and when the a/c was switched off it would drop the cooling somewhat, but not fully.  Then about 15 mins later the car would suddenly and almost instantly, steam up, so it must go down to a pretty low level.

 

There's no odd noise under the bonnet.   The main cooling fan goes on and off with the a/c button but that's not particualrly noticable.

 

The compressor did fail on daughter's Ateca at about 40K miles but I don't know what was wrong with it.  As best I could see the drive "clutch" on the front looked OK.

Edited 25 August, 2023 by Rory

[xman]

I believe it's around 2%

 

https://axleaddict.com/auto-repair/Variable-Displacement-Compressors

[Rory]

Here's a very short sound clip - the click is me turning off the a/c.

[xman]

Why not take it to a dealer and see if its a warranty job?

[Rory]

I will do, but just wanted, as per the title, to see if they're all noisy.  I hate dealing with dealer service departments - it's the kind of thing where they'll say no fault found, or want to charge me for diagnosis or regassing.

 

Earlier in the week I emailed the sales guy we dealt with, more as a holding thing than anything else.  Had nothing back although my wife thinks he was about to go on holiday.  An OOTO message would have confirmed that though.