Octy2 - Elegance 1.9tdi - 33,500km. The noise is almost imperceptible sometime and for people not hearing well. I first heard it when waiting in line at a customs, after advancing some meters and stopping, after the rev of the engine came to idle, there were some additional noise that wasn't suppose to be there (wasn't there for two years since I have the car). After that I have identified the noise to be from the air conditioning system. During a night, in silence, I have heard the noise and when I turn off the air con (I have the dual zone climatronic) the noise stops. When I turn on the air con again, whatever the speed of the fan, the noise is back.

Now, the noise is round, faint, but I am now used to the 'freqency' and I can hear everytime I stay at a red light. Sometimes is stronger (though pretty faint) sometimes it is kind of coming and going. It is a round faint noise, from something turning, bringing almost imperceptible (but I sense those) vibrations in the steering wheel as well as in the gear shift (in the octy tdi all vibrations go trough the car). So it have to be something in the air condition system in the engine compartment (so I guess, it seems to be further than in the dashboard (anyway the sound is the same at any speed and any air direction setting).

I've been to the dealer and they only could empty the aircon and fill it back again (checking for less freon, but it was ok), of course with no result. After I left I was thinking the air con must have some kind of clutch to have the compressor running at the same speed whatever the rev of the engine. Is it so? Then the sound makes me think of a ball-bearing 'thing', or some kind of clutch, that are a little out of center or smth, so they make a round, kind of buzzing noise.

Anybody can tell me what can be turning in and around the air con so it can buzz faintly but audible in the car (it can't be distinguished from the sound of the engine when you are in the front of the car, hood up or not)? A ball bearing, a clutch, anything else around the compressor (I hope it is not inside the compressor, that one being expensive to replace). My Octy has just came out of the warranty :(

Thanks!!

More than likely a flap motor operating.

could you elaborate that please? what flap, what motor? there was no such sound for 33,ooo km

The a/c system uses motors for flap actuation. As the control unit monitors temperatures in different zones is more flaps within the a/c system to regulate temperature. After a time these motors can get noisy or loose thier basic settings meaning the will try to operate past thier end stop.

I see now what you meant. But it is not that. I can hear those flap actuation motors when the engine is starting, when I change the settings or, as you said, the climatronic changes the settings by itself. I know the sound of those motors, and they are silent and stop after the movement is done.

But this noise I am trying to get rid off is from the engine compartment, from the drive of the compressor, as I said some bearing there, the clutch or smth (whatever transmits the motion from the main axe to the air con).

But thanks for the hint .. could have been that but unfortunately it is not. Those are ok :(

There isnt a clutch on the compressor, its constantly driven.

Your aren't hearing the noise of the refrigerant (freon as you call it) boiling off through the evaporator are you?

Turn the climatronic to ECON and see if the noise goes away.

Or is it an electric fan on the condenser coil right at the front of the car, again try turning on the ECON to see if it goes.

My money is still on a 'lost' damper motoring constantly thus generating a gentle humming noise.

Yes it can be described as a 'gentle humming noise' and could be from a electric fan if there is any - because if there is no clutch and the spin of other parts are variable speed - this sound stays the same no matter the rev of the engine or the speed or temperature of the climatronic. I will try pushing the ECON and listening if it goes away? What electric fan is that on the condenser coil? Is is visible? Where I can see it to point it to the dealer to check it out? What do you mean by 'lost damper motoring'?

There will be an electric cooling fan on the condenser coil - the part that rejects the heat from the air conditioner, it will run when the ECON light is OFF.

The condenser fan will be between the engine and the radiator coil as that's the area where the condenser is located. This is the most unlikely cause of the noise.

The damper - or flap- motors make a gentle humming noise when they work, if one is confused it will get 'lost' or stuck. This means the climatronic doesn't know what position the flap is in so it keeps running to try and get to where it should be.

Try turning on the ECON first and see if the noise goes, if it doesnt then it's likely to be a flap motor.

I have also experienced what you have described. When the air con. is switched off the intermitent humming noise goes away. To me it sounds like a dry bearing sound. Unfortunately I don't think it is loud enough to convince my dealer to do anything about it. My car is just over a year old, will be interested if you get to the bottom of it!

If it intermittent and goes off with the air con, it is probably one of the aforementioned flap motors lurking behind the dash.

Either the flap mechanism is jammed and the controller is trying to push it to where it wants and obviously can't. Or the flap has got lost, the controller no longer knows where the flap is so it is blindly driving it when it has probably reached the limit of it's travel.

If it is one of the above, it will have a detrimental effect on your climate control.

The noise is also dependent on engine revs as previously described by "bugs". If the engine revs are increased slightly the noise goes away and after a few seconds will come back as the dry bearing sound.

yes it is a bearing noise, it is NOT from the dashboard but from the engine compartment, to be clear on this .. I hope next week to be able to check at the dealer that electric fan - I've called them and they agreed with that probability .. I will write here after trying the fix .. my car is two years old exactly and I have 34.100km

There is a known issue with a 'clicking' noise from the dashboard as well.

Yeah mine does that!

Every now and again a metallic "clink" from somewhere on the dash, sounds like up near the cubby hole or around the windscreen area, probably due to expansion.

Thats in addition to the clicking from the black plastic piece between the 2 metal outlet grilles for the windscreen (I.R. Sensor?)

Good luck at the dealer bugs, hope they sort it this time

The problem noise eminates from the right side of the dashboard and requires replacment of the Dual Zone unit.

God..........:(

*adds to list of stuff to whinge to dealer about when in for it's first service*

There is a known issue with a 'clicking' noise from the dashboard as well.

yes I do have the very fade "clong clong clong" plastic/rubber noise but only I push the button to direct the air to the feet :( that is why I leave it on Auto hoping that it will not start to do this also on Auto

still not managed to get to the dealer for the other sound .. I have tried .. it does stop at the moment I push the ECON .. so it must be the electric fan on the condenser coil

Does the sound go still when you increase engine revs. if so the electric fan would not be driven by the engine belts and I would guess not be effected. Unless the motor speed is variable in some way?

check my first post .. it is not dependable of the engine rev .. that is what I have asked .. and now I am pretty sure that is the electric fan .. I guess we have the same noise .. but when you rev up the engine we can't hear anymore the electric fan that is probably zzumzzimg because of lack of grease or out of balance .. check yours at the service (dealer)

bugs, have you had the noise looked at by the dealer yet? Mine is booked in for the 27th of this month. It has got a bit louder now so should be easier to demonstrate to the dealer!!

yes, I went to the dealer, but unfortunately the car is reluctant to show defects when taken to the mechanics, so the noise was almost imperceptible from the interior, I could not demonstrate, and the noise can't be heard from the front of the car, looking at the engine, because the engine noise covers the other .. they told me to get back when I have a louder noise :( now it is daily .. I will take it later this year again .. maybe when I will install my cruise control .. I've heard it is a simple operation to install it by changing the left lever behind the wheel (the one for signaling turns left/right)

maybe when I will install my cruise control .. I've heard it is a simple operation to install it by changing the left lever behind the wheel (the one for signaling turns left/right)

Slightly more involved than that, you also need to make sure your car has a suitable steering controller.