# Crackling Noise when front windshield defrost in use (TOC)



## PhirstVW (Mar 23, 2008)

*Crackling Noise when front defroster fan engages*

Sounds like dried leaves being tossed around upper dashboard, that fell in some way. Or, is this something else?
Jim


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## car_guy (Aug 19, 2005)

*Re: Crackling Noise when front defroster fan engages (PhirstVW)*

Can you clarify? Do you hear this only when the 'Defrost' button on the dash is pressed or whenever the HVAC fan is blowing in any mode? Do you hear it at any fan speed? Have you checked to see whether the two filters that are attached to the underside of the hood (appear black due to charcoal) are actually there? These would keep debris from getting into the system which is usually the cause of the noise you are reporting.
Steven


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## PanEuropean (Nov 3, 2001)

*Re: Crackling Noise when front defroster fan engages (PhirstVW)*


_Quote, originally posted by *PhirstVW* »_Sounds like dried leaves being tossed around upper dashboard, that fell in some way...

Hi Jim:
That is likely exactly what the problem is. 
One of the Phaeton owners in my community (Dyne) has the same problem. The recommended solution is to remove the dashboard, which is an awfully complicated task that I would only do as a last resort - there is too much risk of screwing a lot of other stuff up when the dashboard is removed, not to mention the likelihood of not getting everything lined up properly when replacing it.
As soon as the weather gets better, Dyne and I are going to get a borescope from my workplace (a specialty tool used for inspecting the inside of aircraft turbine engines) and shove the tip of the borescope down the defrost vents until we find the leaf. Once we find it, we plan to then use a small spring-loaded claw to grab the leaf and pull it up through the vent.
When we do this, I'll take pictures and write up a how-to. My guess is that the task will only take a few minutes.
I believe that borescopes are also used for some surgical procedures, that might be an alternative source for one if you know someone in that trade. They are quite expensive (ca. $25K for a good one), it's not the type of tool that a car dealership would have on hand.
Michael


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## GS340 (Oct 26, 2007)

*Re: Crackling Noise when front defroster fan engages (PhirstVW)*

I had a similar/same issue when 'Defrost' button on the dash was pressed or whenever the HVAC fan is blowing HOT air up through the metal dash vents. When I had COLD air blowing up through the metal dash vent there was no sound. 
If you have the same issue DO NOT REMOVE the DASH!!!!! 
You won't be able to get to the leaves. To remove the leaves once they've enter the AC system is done via the blower fan. The leaves are sitting right next to the outside face of the heater core. Have the dealer remove the blower fans and the tech can reach in and vacuum out the leaves. 

The first dealer I visited said I had to pay $3000 to remove the dash because the leaves are right next to the defrost vent or stuck in the upper part of the dash. Or I had to remove the windshield and try to fish them out that way. I said NO WAY. The tech let me borrow his service book where i found pictures of the AC system. The pictures showed that the heater core acts as a filter since all the air has to pass through the core to get inside the cabin. I went back to the dealer and the tech didn't want to touch the car which really pissed me off. He said the leaves are past the core and i asked him then WHY don't we hear the sound when I blow COLD air up through the same vents? No answer...









I ended up at another dealer and showed him the copies of the tech's manual I made and showed him how the sound only happens with the heat on blowing UP or defrost. He agreed, and said it would be worth going in from the blower side.
In the end i was right... so I hope this helps.
Dealer charged me $300 for labor to remove the blower fans and clean out the leaves. 



_Modified by GS340 at 3:46 PM 12-21-2008_


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## GS340 (Oct 26, 2007)

*Re: Crackling Noise when front defroster fan engages (GS340)*

I found this picture in another thread. in my case and I'm sure you are having the same issue the leaves were right next to the heat exchanger but it could have been the evap. But in any case once the fans are removed it was an easy clean up.
to answer the question how did they get in there. When I was at the second dealer we opened the hood and noticed that leaves were getting behind the filters around the wiper arms. there were several small leaves and parts of larger leaves that had already worked their way half way past the plastic screen and when the tech tried to remove them one broke in half and fell down to the blower fan!!

















_Modified by GS340 at 5:27 AM 12-21-2008_


_Modified by GS340 at 5:33 AM 12-21-2008_


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## GS340 (Oct 26, 2007)

*Re: Crackling Noise when front defroster fan engages (GS340)*

Here is another good picture. You can see the fans, evap, and the heater core behind the evap.


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## PhirstVW (Mar 23, 2008)

*Re: Crackling Noise when front defroster fan engages (GS340)*

Thank you. Very helpful. I will approach the service tech with these notes for assistance.
Jim


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## KCPhaetonTech (Aug 17, 2008)

*Re: Crackling Noise when front defroster fan engages (PanEuropean)*


_Quote, originally posted by *PanEuropean* »_
I believe that borescopes are also used for some surgical procedures, that might be an alternative source for one if you know someone in that trade. They are quite expensive (ca. $25K for a good one), it's not the type of tool that a car dealership would have on hand.
Michael

Actually I have 2 of them at work. One has a LCD screen that can record video that I payed $400 and the other just an eye to inspect. Sure would like to get my hands on one of those $25K scopes!


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## PanEuropean (Nov 3, 2001)

*Re: Crackling Noise when front defroster fan engages (GS340)*


_Quote, originally posted by *GS340* »_...To remove the leaves once they've enter the AC system is done via the blower fan... 

Thanks very much for that advice Robert. We'll stuff the borescope in through the air intake under the hood and see what we can find from that end of things.
Michael


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## eurolok003 (Mar 16, 2009)

*Re: Crackling Noise when front defroster fan engages (PhirstVW)*

I am having exactly the same problem with my car. My dealer says the leaves can be sucked out. He doesn't look surprised hearing me describing the russling noise coming from the base of the windshield w/ defroster on. Maybe it happens quite often for phaetons? Why though?


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## PanEuropean (Nov 3, 2001)

*Re: Crackling Noise when front defroster fan engages (eurolok003)*


_Quote, originally posted by *eurolok003* »_ Maybe it happens quite often for Phaetons? Why though? 

It seems to depend on where you park your car. If you park outside, and happen to park under a tree (for example, there is a tree on your property), then debris from the tree falls onto the car. The leaves and needles that fall on the windshield can eventually work their way into the air intake system.
The easiest way to check and see if this problem exists is to have a look in the plenum areas behind the engine bay, on the outboard corners of the car. There is an illustrated post in the TOC that explains how to do this.
Michael


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## rick100 (May 28, 2007)

*Re: Crackling Noise when front defroster fan engages (PhirstVW)*

Before you settle on the problem being leaves... There is another possibility. 
I was quoted to remove the dash after a failed attempt to blow out these supposed leaves. I finally broke down convincing the warranty desk to pull the dash apart- It wasn't leaves at all. It was some thin film material that is part of the ducting that had worked its way into the fan blades. The tech cut it back a bit, and no sound anymore- The bill was $0 under the factory 50k warranty.
(they would NOT have covered it if it were, in fact, leaves!)
Richard


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## PanEuropean (Nov 3, 2001)

*Re: Crackling Noise when front defroster fan engages (rick100)*

Hi Rick:
Thanks for posting that information, it is most interesting.
A Phaeton owner in my neighborhood has a very pronounced problem with a rattling noise whenever the defrost is in use. I am going to borrow a borescope from work (a tool we use to look inside aircraft engines) and stuff it down the defrost outlets and see what can be found there.
We took the fan apart (from under the hood) last weekend, but could not find any debris in the fan assembly.
Michael


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## rick100 (May 28, 2007)

*Re: Crackling Noise when front defroster fan engages (PanEuropean)*

Michael,
I'm taking the car in for it's last free service (49,678 mi right now!) this week, and will ask the Phaeton Tech for better detail of what the thin film material was from. The work order actually had a sample of the material he trimmed taped to it. He should be able to describe where the material came from- I mistakenly stated previously that this was actually touching the fan blades. I am actually not certain where this was, all I know is that it definitely sounds like leaves rustling around. I may take in the schematics/cartoons in this thread so he can point out exactly where this material is from.
Richard


_Modified by rick100 at 8:44 PM 3-31-2009_


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## PanEuropean (Nov 3, 2001)

*Re: Crackling Noise when front defroster fan engages (rick100)*

Hi Richard:
Thanks ever so much for offering to do that - a bit of guidance about where to look would be very helpful. A borescope is a useful tool, but has a somewhat limited field of view (only about 25°) - so, it would be great to know where to begin to look.
Michael


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## car_guy (Aug 19, 2005)

*Re: Crackling Noise when front defroster fan engages (rick100)*

Remember to ask them to do a brake fluid flush if it hasn't been done within the last two years. It should be covered as a free service.
Steven


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## dovetaildoc (Jan 3, 2009)

*Noise in front window defroster*

With the change in weather, the front defrost fan is kicking on and there is something rattling around with the fan. Sounds suspiciously like a leaf or a piece of stiff paper rattling around in a fan chamber. 
I was wondering if I can get to the area through the cabin air intake by removing the debris screen as described in the "Water in the front footwell" thread so nicely described by Michael?
Mike


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## GS340 (Oct 26, 2007)

*Re: Noise in front window defroster (dovetaildoc)*

I had the same issue. First time around dealer A said it was leaves around the blower fan. He cleaned them out and all was good. Dealer A also mentioned that he had another phaeton the year before with the similar sound and it turned out to be a piece of plastic from the back side of the duct work foam insulation. 
The leaf fix lasted about 8 months... Sound was back so I took it to another dealer. Dealer B said something got sucked up inside and they called VW American and they sent someone out. They looked around for two days and were about to take the dash out when one of them deciede to reverse the polarity of the blower fan. Now the blower fan is pulling air from the inside of the car. He said he let the car sit with the blower running for 3 hours and pieces of something finally few out. He's not sure what it was but whaterver it was got cut up and shot out. VW America paid for half the bill which was about $1000 total for 10 hours of labor. 
to this day the sound hasn't come back. Dealer A said VW America covered the dash removal once it was determined that the sound was from part of the car vs a leaf or something else.

There are other folks on the forum with the same issue and I believe it's the plastic backing from this foam or whatever Dealer A pulled out of the other phaeton. 

I didn't go back to Dealer A because someone damaged the car. Long story... 

Troy is the phaeton Tech at Lindsay VW of Dulles VA (dealer B). Give him a call at 1-888-656-2611... Tell him you have the leaves in the dash sound.... He should point your dealer in the right direction. At least give them the number for the guy that came out from VW America. 
EDIT:
Links to my old posts.... The first time around I think the dealer got lucky even though there was leaves around the blower fan. I think whatever was inside got lodged someplace and worked it's way loose after 8 months. 
I stopped by when troy was working on the car and he had the blower fan out. I don't see how anything could get pushed past the evaporator and I don't understand how whatever blew out got sucked past the evaporator. All i know is that sound drove me crazy for a @#[email protected]# year!!!!!!!!!!!







































































Knock on wood that it never comes back.

http://forums.vwvortex.com/zerothread?id=4170251
http://forums.vwvortex.com/zerothread?id=3740525



_Modified by GS340 at 5:02 AM 12-6-2009_


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## zenmoused (Nov 6, 2008)

Same problem here. It's super annoying but there's no way I'm paying to have it fixed.


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## remrem (Jan 20, 2008)

*Re: Crackling Noise when front defroster fan engages (GS340)*

Hi guys,
Since some of you apparently have a good understanding of the workings of the climate control system, perhaps you could take a look at this thread:
http://forums.vwvortex.com/zerothread?id=4493412
You will read that I have been experiencing a weird problem that has recently provided another symptom and thus perhaps another clue. I am taking my car in tomorrow for service and plan to have my Phaeton tech take another look, so any insights and advice you can offer would be greatly appreciated. As good as he is, I'm fearful he's going to recommend removing the dashboard, or say he can't find a problem. Thanks very much.
Regards,
Ron


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## remrem (Jan 20, 2008)

*Re: Crackling Noise when front defroster fan engages (remrem)*

Hello again guys. I was hoping one of you might have some comments or suggestions. Click here to read my orignal post - http://forums.vwvortex.com/zerothread?id=4493412 and then return here to read the following update...
My car's been in the shop for a week. I have the greatest confidence in my Phaeton tech, but we're getting to a critical point. He thought he had determined it was a faulty Pump Valve Unit (pg. 20 of the design document), but when he replaced it with a new one, the problem remained. He says VW is now advising him it's either a bad sensor (I'm not sure which one) or a failed heat exchanger. If they decide it's the heat exchanger I fear he will declare that a dashboard disassembly is required! As meticulous and talented as he is, I'm already hearing the squeaks and rattles in my head! 
Any comments, guesses, insights, etc. would be greatly appreciated.


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## PanEuropean (Nov 3, 2001)

*Re: Crackling Noise when front defroster fan engages (remrem)*

Hi Ron:
I wish I could help, but I really don't have any more information I can add. I tried troubleshooting one of these "rattling noise when defrost is in use" problems about a year ago (someone else's Phaeton) - spent a day working on it, using an aircraft borescope to probe through as many ventilation ducts as I could get access to without drilling holes - no luck, could not find the cause of the problem.
If I take this task on again (the problem Phaeton is in my neighborhood), what I will probably do is drill small holes (1/4 inch) in some of the PVC air ducting to let me get the borescope into areas I could not reach via normal pathways before. I will then be able to plug these holes using standard aircraft industry PVC plugs (thus, the whole business of poking holes will be mil-spec.).
Best guess I can offer is that the cause of the problem is not a leaf or some other foreign object, it's probably a label or a piece of insulation - in other words, something domestic to the car.
Michael


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## remrem (Jan 20, 2008)

*Re: Crackling Noise when front defroster fan engages (PanEuropean)*

Hi Michael,
Thanks for your response. I'm sorry, but it was late and I was a little foggy when I wrote my post last night, so I may have caused some confusion. I realize now I should have entered it into my original discussion thread describing my problem, which is not about noises emitting from my climate control system (mine is perfectly quiet), but about incorrect temperature of air outflow from the vents. The only noises I have are the ones I am *forecasting* if my tech has to disassemble my dashboard.








So, for continuity and clarity I am going to copy my post above and insert it where I should have in the first place. Thanks again.
Ron


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## Rosendo (Mar 23, 2014)

*Do new chinesse-production Phaetons have that problem nowaday?*

I wonder...?


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## PanEuropean (Nov 3, 2001)

Rosendo said:


> Do new Chinese-production Phaetons have that problem nowadays?


Uh, I am pretty sure that no Phaetons are built in China. They are all built in Dresden. Many are exported to China. I believe that the HVAC system design is the same for all markets.

Michael


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## anthonymck (Mar 8, 2012)

*same crackling noise*

has anyone gotten this fixed? What was the estimate for the "reverse polarity" approach for the motor? I am actually getting accustomed to the sound now - almost like a special feature!


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## Phaeton2 (May 18, 2013)

Can the photos be rehosted? I tried the reverse polarity approach and it didn't work for me. You can search my threads for photos showing how I did it.


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## PanEuropean (Nov 3, 2001)

Hi Steve:

I can only re-host photos that were mine originally - I have no archival record of GS340's photos.

But - if you go and have a look at this discussion: Water in Cabin Footwell (Cleaning Air Intake Plenum and Sunroof Drains) I think you will find similar photos that illustrate the problem of debris in the cabin air intake plenum.

Michael


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