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Go Back   TDIClub Forums > TDI Model Specific Discussions Areas > VW MKIV-A4 TDIs (VE and PD)

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 July 8th, 2010, 07:13   #1
STRANGETDI
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Default New engine noise when A/C on!

Hi all,

I hope you can help with this issue that arose this morning.
I now have a clicking noise when the air conditioner is on. This is what happened: I started the car to go to work this morning. I turned on the A/C (fan setting 1) after about 20 seconds of idling. I back out of the drive way with no problem, as soon as I shift to 1st and go forward (I get this clicking noise that increases with engine speed) Everything is working fine, but I now get this noise. At some point when I reach a speed high enough, I donít hear it anymore (engine may be to loud at this point). When I decelerate, I donít think I hear it at all or as much (as the engine is still loud when decelerating). Any ideas?

I turned off the A/C for my commute, but I only continued to test this at stop lights, and it happened everytime.

Is this a sign that something may be on itís way out?

Thanks,

Chris
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CURRENT: 2013 Audi A3 2.0T (Gas) Premium Plus Quattro - APR Stage 2
Gone: (Buyback 4/18/18) 2012 GOLF TDI w/ TECH, 4DR, 6SP MANUAL, 121K miles
OLD: 1999.5 Golf GL TDI,Up'd,.216s,17 OZ Rims,Eibach Pro-Kit&Dampers,TT SS 2.5" Exst. 222,000 - Sold to Rossman83
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Old July 8th, 2010, 08:00   #2
scurvy
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It's hard to tell from your post, but I take it that you're now getting a clicking noise that keeps tempo with the engine speed. It would help to clarify the following points:

Does it happen every time you're moving forward?

Does it only happen when you're using the AC?

If you're driving along and can hear the clicking, what happens if you shift into neutral - does the clicking continue with the vehicle's speed or does it abruptly fall off as the engine goes to idle?

Does it get better / worse / stay the same as you swerve right or left and/or make sharp right / left turns?

CV joints going bad typically make a clicking noise in turns but it could also be many things. You need to diagnose it better before anything can be looked into further.
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Old July 8th, 2010, 08:08   #3
Ski in NC
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Does noise occur only when ac is on? No noise with ac off?

If so, could be ac clutch or alternator pulley issue. AC clutch central nut is notorious for backing out, and can easily be tightened. Alternator pulleys are one-way clutches, also notorious for failure once the years and miles rack up. Alt shares same belt as ac. Tensioner can also wear out.
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2001 Jetta TDI 5sp Stock 201k mi
1981 Rabbit IDI 4sp Sold at 339k mi
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Old July 8th, 2010, 10:01   #4
STRANGETDI
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Quote:
Originally Posted by scurvy View Post

Does it happen every time you're moving forward? YES

Does it only happen when you're using the AC? YES

If you're driving along and can hear the clicking, what happens if you shift into neutral - does the clicking continue with the vehicle's speed or does it abruptly fall off as the engine goes to idle? FALLS OFF AS ENGINE GOES TO IDLE

Does it get better / worse / stay the same as you swerve right or left and/or make sharp right / left turns? I'LL HAVE TO TRY THIS AND SEE

CV joints going bad typically make a clicking noise in turns but it could also be many things. You need to diagnose it better before anything can be looked into further. NOT CV JOINT, ALMOST POSITIVE
Thanks
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CURRENT: 2013 Audi A3 2.0T (Gas) Premium Plus Quattro - APR Stage 2
Gone: (Buyback 4/18/18) 2012 GOLF TDI w/ TECH, 4DR, 6SP MANUAL, 121K miles
OLD: 1999.5 Golf GL TDI,Up'd,.216s,17 OZ Rims,Eibach Pro-Kit&Dampers,TT SS 2.5" Exst. 222,000 - Sold to Rossman83
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Old July 8th, 2010, 10:05   #5
STRANGETDI
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Quote:
Originally Posted by Ski in NC View Post
Does noise occur only when ac is on? No noise with ac off? This is correct.

If so, could be ac clutch or alternator pulley issue. AC clutch central nut is notorious for backing out, and can easily be tightened. Alternator pulleys are one-way clutches, also notorious for failure once the years and miles rack up. Alt shares same belt as ac. Tensioner can also wear out. Interesting, very possible, but don't know at this point.
Thanks.
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Chris
CURRENT: 2013 Audi A3 2.0T (Gas) Premium Plus Quattro - APR Stage 2
Gone: (Buyback 4/18/18) 2012 GOLF TDI w/ TECH, 4DR, 6SP MANUAL, 121K miles
OLD: 1999.5 Golf GL TDI,Up'd,.216s,17 OZ Rims,Eibach Pro-Kit&Dampers,TT SS 2.5" Exst. 222,000 - Sold to Rossman83
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Old July 8th, 2010, 10:14   #6
STRANGETDI
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Quote:
Originally Posted by Ski in NC View Post
Does noise occur only when ac is on? No noise with ac off?

If so, could be ac clutch or alternator pulley issue. AC clutch central nut is notorious for backing out, and can easily be tightened. Alternator pulleys are one-way clutches, also notorious for failure once the years and miles rack up. Alt shares same belt as ac. Tensioner can also wear out.

Where is this AC clutch central nut located?

I do have 191,000 miles on it.
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Chris
CURRENT: 2013 Audi A3 2.0T (Gas) Premium Plus Quattro - APR Stage 2
Gone: (Buyback 4/18/18) 2012 GOLF TDI w/ TECH, 4DR, 6SP MANUAL, 121K miles
OLD: 1999.5 Golf GL TDI,Up'd,.216s,17 OZ Rims,Eibach Pro-Kit&Dampers,TT SS 2.5" Exst. 222,000 - Sold to Rossman83
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Old July 8th, 2010, 10:18   #7
Ski in NC
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Nut is right in the center of the ac clutch. 14mm I think. A little tight there to get a wrench in. Some car stuff is in the way. Easiest to get to from the bottom with some of the plastic junk moved out of the way. Need to hold clutch while tightening nut.

Mine was loose at 115kmiles. Put the hoodoo on it and it has stayed tight.
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2001 Jetta TDI 5sp Stock 201k mi
1981 Rabbit IDI 4sp Sold at 339k mi
1990 S-10 4.3 4wd 5sp 154k mi
1986 VW Pathfinder 1.6 45hp Marine 4700 Hrs
2001 Cummins 8.3 420hp Marine 1660Hrs..REFIT DONE!!
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Old July 8th, 2010, 10:33   #8
scurvy
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Quote:
Originally Posted by STRANGETDI View Post
Does it happen every time you're moving forward? YES

Does it only happen when you're using the AC? YES

If you're driving along and can hear the clicking, what happens if you shift into neutral - does the clicking continue with the vehicle's speed or does it abruptly fall off as the engine goes to idle? FALLS OFF AS ENGINE GOES TO IDLE
So it's definitely something before the transmission even though the first and second statements are incongruous - you don't ALWAYS have the AC on, do you?

I would check the AC compressor clutch nut as Ski in NC mentioned, it is 14mm. Also check the area around the compressor/serp belt to make sure there's not a twig or leaf in the area.

Has the AC changed effectiveness recently?
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Old July 8th, 2010, 14:25   #9
STRANGETDI
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Quote:
Originally Posted by scurvy View Post
So it's definitely something before the transmission even though the first and second statements are incongruous - you don't ALWAYS have the AC on, do you? It only happens when the AC is on when moving forward. This only started to happen this morning.

I would check the AC compressor clutch nut as Ski in NC mentioned, it is 14mm. Also check the area around the compressor/serp belt to make sure there's not a twig or leaf in the area.

Has the AC changed effectiveness recently? Nope, seems to work fine.
Thanks. I'll check my Bentley Manual for this nut location. I do my own repairs when I can, so if this is easy. I think I can do this.

What do you mean, hold the clutch when tightening the nut? It may seem self explanatory when I get in there.
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CURRENT: 2013 Audi A3 2.0T (Gas) Premium Plus Quattro - APR Stage 2
Gone: (Buyback 4/18/18) 2012 GOLF TDI w/ TECH, 4DR, 6SP MANUAL, 121K miles
OLD: 1999.5 Golf GL TDI,Up'd,.216s,17 OZ Rims,Eibach Pro-Kit&Dampers,TT SS 2.5" Exst. 222,000 - Sold to Rossman83
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Old July 12th, 2010, 19:12   #10
SheeB
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When you go to tighten the 14mm nut, the clutch assembly will just spin.
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Old July 13th, 2010, 18:47   #11
PolitesTDi
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If I need an A/C clutch only (compressor is fine) where do I find one? Do I have to piece it together myself or can I buy a kit?
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Old July 13th, 2010, 20:01   #12
Dunno513
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Have you taken a look at the area around the AC Compressor... Almost sounds like something is up against the compressor and the compressor engagement disk is hitting something when it is spinning. If not it sounds like it's something internal to the compressor.
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Old July 13th, 2010, 20:21   #13
PolitesTDi
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When I engage the A/C the noise stops, my buddy says it's because the magnet engages and pulls the clutch up far enough that it stops rattling (or something like that). No A/C cooling, so I'm guessing it's internal anyway.
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Old July 14th, 2010, 06:32   #14
STRANGETDI
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Thanks for the suggestions guys. It turns out the issue was a bad tensioner, causing the belt to vibrate and shake to be audible when the A/C was on. New belt and tensioner goes in on Monday. Hopefully it doesn't go in the next few days. Knock on wood......
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Chris
CURRENT: 2013 Audi A3 2.0T (Gas) Premium Plus Quattro - APR Stage 2
Gone: (Buyback 4/18/18) 2012 GOLF TDI w/ TECH, 4DR, 6SP MANUAL, 121K miles
OLD: 1999.5 Golf GL TDI,Up'd,.216s,17 OZ Rims,Eibach Pro-Kit&Dampers,TT SS 2.5" Exst. 222,000 - Sold to Rossman83
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Old July 14th, 2010, 08:49   #15
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Might be safer to just take it off till then...

I have read where at least one serp belt became shrapnel for the TB. I'm not a gambling man when it comes to cars, especially this one.
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