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VW MKIV-A4 TDIs (VE and PD) This is a general discussion about A4/MkIV Jetta (99.5-~2005), Golf(99.5-2006), and New Beetle(98-2006). Both VE and PD engines are covered here.

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Old August 19th, 2008, 13:08   #1
cfinelli
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Join Date: Jun 2005
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Default 2002 Jetta TDI; AC noise or something worse?

All,

I've checked the FAQ and some of the older posts, but nothing looks similar (not sure if that is good or bad).

Our trusty Jetta (2002 TDI, 98,000 miles) has been whining a bit lately. There is a softish noise from near the engine compartment, maybe in the dash or beyond. It's kind of a soft horn sound (oboe?), lasts for a second or so. It seems to be associated with the vent fan motor or AC (occurs reliably if the AC/fan has been running then shut down, either by switching the fan switch off or shutting the engine), but has also occured at other random times. I tend to favor that it is a dying vent fan motor or bearing, but would like some advice from the collected wisdom on this forum.

Anyone have anything like this? Is it likely AC or fan? Since it does occur at the time the engine is turned off should I be worried about something associated with the turbo or fuel system.

We've got 2000 miles left on warranty, so if it is something major we want VW to cover it.

Thanks.

Chris
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Old August 20th, 2008, 12:16   #2
mrGutWrench
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__. This is a long shot ... The noise sounds like my alternator pulley before it died. I guess there's some chance that using the A/C puts more load on the serpentine belt etc. so maybe there's some link.

__. I'd check the serpentine belt first, both the belt and its tensioner. It's probably not the alternator pulley but it's probably something near there.
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Old June 30th, 2009, 20:47   #3
nikbristow
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Fuel Economy: As high as 48. Usually 39 or 40 in mixed driving
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I'm experiencing the same thing with my '02 Golf. I can't hear the noise from under the hood, only inside the cabin.

Here's how it breaks down:

AC is off but vent fan is still on: no noise.
AC is on: noise

I'm really starting to think it's like a bearing in the blower motor. Is it hard to replace? And why would it only whine when the AC is engaged? Is it because the air being cold causes the bearing to whine?

Also, and I thought this was related but now I'm thinking it's not. Every once in a while the AC cuts out for a bit and the air blows stale. I've checked operation of both of my fans at low speed per the AC Sticky, they both work. I'm pretty sure this is completely unrelated. But just in case.
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Old July 1st, 2009, 21:16   #4
streeker02
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A/C Compressor clutch would be my guess.
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Old July 2nd, 2009, 03:31   #5
DanG144
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I hear a noise on a lot of A4's and A5's when the engine is shutdown and the AC has been on. A whine or drone.

It can last for several minutes. It seems to be the liquid refrigerant bleeding through the temperature control valve (expansion valve or thermal expansion valve - TXV) for the AC evaporator.

Perhaps this is what you are hearing? I think it is perfectly normal, as the TXV throttles down to try to keep the evaporator from going below 32 degrees F.
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Old July 8th, 2009, 10:25   #6
nikbristow
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Fuel Economy: As high as 48. Usually 39 or 40 in mixed driving
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Well, part of my problem is solved.

Took it to a shop here in Atlanta that has always shot me straight. They said I was low on freon because of several leaks. They're replacing the high and low pressure valves and also the expansion valve and recharging the system.

I'm betting that when I get it back this afternoon the blower motor, if it was indeed the blower motor, will be whining like crazy. It would only whine before when the air was blowing cold. In theory, constant cold air will cause constant whining.

If so, I've got a used blower motor from ebay I'll install.

If by some chance the motor doesn't whine with the fixed AC, I've got a blower motor from ebay for sale if anyone's interested.
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Old July 23rd, 2009, 14:03   #7
nikbristow
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Mostly fixed. The AC blows ice cold now that the leaks are repaired and the mysterious whining has 99% gone away. I'm pretty positive that the blower motor was indeed making the noise, and the constant change between warm, wet air and cool, dry air was causing it to make noise. With the air consistently cold now, it doesn't whine. I have heard it whine, very lightly on two separate occasions. Both times were when I had the vent blowing and then turned on the AC. But they were almost not audible. In time the blower motor may again start whining more frequently but I think I'm putting that blower motor back on ebay and considering my problem solved. Hope this helps.
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