2004 Audi TT 225 roadster a/c clutch won't engage

harr2969 · Apr 8, 2017

Hey guys, I've spent hours learning the car's HVAC system and I'm pretty well educated at this point.

I *previously* had this error: 00792 - A/C Pressure Switch (F129) 00 - Open or Short to Ground

I added some r134, bringing the static pressure (read with physical gauges) to about 50psi. (will add more once the compressor is engaging) Since I added that, there are no errors in the system. It's held a few days, and I haven't seen/found any leaks.

I have the g65 switch, so I can't jumper the f129 a-b terminals as many would think.

Is it possible to jumper the wires some other place rather than checking / applying 12v right at the compressor? That seems really awkward but it looks like that's the next step.

I also haven't found a guide to replacing the clutch on its own without taking the compressor out. Any feedback?

Resources I found:
http://forums.ross-tech.com/showthread.php?633-Tis%92-the-HVAC-Season&highlight=compressor+clutch
http://www.ross-tech.com/vcds/tour/b-settings.php

Thanks in advance for any pointers....

Code:

Saturday,08,April,2017,13:04:02:17476
VCDS -- Windows Based VAG/VAS Emulator Running on Windows 10 x64
VCDS Version: 17.1.3.0 (x64)
Data version: 20170320 DS267.7
www.Ross-Tech.com

Dealer/Shop Name: Home
Workshop Code: 444 04738 087694

VIN: TRUUT28N641004001   License Plate: 
Mileage: 107874   Repair Order: 


Chassis Type: 8N (8N - Audi TT (1999 > 2007))
Scan: 01 02 03 08 15 17 22 35 37 45 55 56 76 77
 
VIN: TRUUT28N641004001   
-------------------------------------------------------------------------------
Address 01: Engine        Labels: None
   Part No: 8N0 906 018 CJ
   Component: 1.8L R4/5VT     G   0001  
   Coding: 07710
   Shop #: WSC 04738  
   VCID: 7BFBE47F69A12499BC-513C
   TRUUT28N641004001     AUZ5Z0C5036104

No fault code found.
Readiness: 0000 0000

-------------------------------------------------------------------------------
Address 03: ABS Brakes        Labels: 8N0-907-379-MK60-A.lbl
   Part No: 8N0 907 379 H
   Component: ESP ALLRAD MK60     0101  
   Coding: 0022544
   Shop #: WSC 01236 785 00200
   VCID: 418756971BCD8E49A6-5178

No fault code found.

-------------------------------------------------------------------------------
Address 08: Auto HVAC        Labels: 8N0-820-043.lbl
   Part No: 8N0 820 043 A
   Component: TT-KLIMAVOLLAUTOMAT D03  
   Coding: 00140
   Shop #: WSC 01236  
   VCID: 2851EB33C8B75F0181-2592

No fault code found.

-------------------------------------------------------------------------------
Address 15: Airbags        Labels: 8N0-959-655.lbl
   Part No: 8N0 959 655 B
   Component: Airbag Front+Seite 6000  
   Coding: 01103
   Shop #: WSC 01236  
   VCID: 3F83506F3D39F8B9D0-515A

No fault code found.

-------------------------------------------------------------------------------
Address 17: Instruments        Labels: 8Nx-920-xxx-17.lbl
   Part No: 8N1 920 980 A
   Component: KOMBI+WEGFAHRS. M73 D06  
   Coding: 05244
   Shop #: WSC 00000  
   VCID: 34690F43047F2BE13D-FFFE
   TRUUT28N641004001     AUZ5Z0C5036104


-------------------------------------------------------------------------------
Address 22: AWD        Labels: 02D-900-554.lbl
   Part No: 02D 900 554 C
   Component: HALDEX LSC  ECC     0010  
   VCID: 2041F313A087A741C9-4B32

No fault code found.

-------------------------------------------------------------------------------
Address 35: Centr. Locks        Labels: 8Nx-962-267.lbl
   Part No: 8N7 962 267 F
   Component: Central Lock/Alarm  D09  
   Coding: 15900
   Shop #: WSC 01236  
   VCID: 438B5C9F51D19C59B4-4F1E

No fault code found.

-------------------------------------------------------------------------------
Address 55: Headlight Range        Labels: 4B0-907-357-AUT.lbl
   Part No: 4B0 907 357 
   Component: LEUCHTWEITEREGLER  D004  
   Coding: 00010
   Shop #: WSC 01236  
   VCID: 65CFA207FF2582697A-51B2

No fault code found.

-------------------------------------------------------------------------------
Address 56: Radio        Labels: 8E0-035-1xx-56.lbl
   Part No: 4B0 035 186 R
   Component: concert II  NP2    0008   
   Coding: 00202
   Shop #: WSC 08219  
   VCID: 2F63002FED59083940-4ECA

No fault code found.

End-------------------------(Elapsed Time: 06:24)--------------------------

Note: a CLEAN scan... YAY... so many hours to get to that point.

harr2969 · Apr 8, 2017

It wasn't too hard to get to it from the top since most of my covers are off. Also took off the bracket that holds the oil dipstick which helped a lot.

The compressor clutch has no electrical continuity / open. Until I wiggle the lead, then it's less than 1ohm / shorted. :-(

Neither of these represent a working clutch. :-) http://www.freeasestudyguides.com/ac-clutch-coil-test.html

I would love to replace the clutch only, not having to take apart the system would be more ideal. Has anyone done this on the TT? Is it feasible?

DrPeter · Apr 10, 2017

Hello,

I would love to replace the clutch only, not having to take apart the system would be more ideal. Has anyone done this on the TT? Is it feasible?

- Good question and Yes! you can replace the clutch on a Sedan 7V16 A/C Compressor which is what I believe this 2004 Audi TT should have installed.

I recommend to contact your local dealer's part department and ask them for the 'electromagnetic coupling', this should come with the clutch coil, the two parts of the clutch and the 'attachment parts' for the 'electromagnetic coupling'.

- The Official Factory Repair Information will explain in detail how to remove, install and adjust the gap of the clutch using the spacers.
Do not skip that step!! It is very important in order to help maintain a long compressor life and proper A/C compressor operation!

And as always, follow all safety guidelines when advised as per the Official Factory Repair Information and use the proper tools and safety equipment.

When in doubt, refer any A/C repair work to qualified professionals.

Hope this helps, stay cool...

drpeter

harr2969 · Apr 10, 2017

DrPeter said:
Hello,

- Good question and Yes! you can replace the clutch on a Sedan 7V16 A/C Compressor which is what I believe this 2004 Audi TT should have installed.

Yep!

I recommend to contact your local dealer's part department and ask them for the 'electromagnetic coupling', this should come with the clutch coil, the two parts of the clutch and the 'attachment parts' for the 'electromagnetic coupling'.

Thanks -- I subsequently found / ordered this one: http://www.ebay.com/itm/222416767291 "AC A/C Compressor Clutch Assembly For Audi TT 00 02-06 TT Quattro 00 02-06 1.8L" which says it will fit and seems to have all the right parts.

- The Official Factory Repair Information will explain in detail how to remove, install and adjust the gap of the clutch using the spacers.
Do not skip that step!! It is very important in order to help maintain a long compressor life and proper A/C compressor operation!

Yes - I've been reading up on that, makes sense. Gap needs to be small without rubbing. https://www.youtube.com/watch?v=RFC5jMhUm4s

And as always, follow all safety guidelines when advised as per the Official Factory Repair Information and use the proper tools and safety equipment.
When in doubt, refer any A/C repair work to qualified professionals.

Psssh :-) I need to use all the tools I bought to work on this Audi

Thanks much for the feedback!

harr2969 · Apr 15, 2017

I've got the clutch disc off, but circlip holding the magnet is deep and my angled pliers won't reach it. The frame is in the way so I can't go in with straight pliers. Taking the compressor off seems like a whole nother level of difficulty, even loosening it from the bracket seems like it would be useless without removing the alternator, which seems too tight to get out without removing the intake. I'm at a loss. Seems like the perfect tool is an extra long angled external circlip pliers, which I can only find in Taiwan, and doesn't seem to be available for purchase online anyway.

http://www.jbtool.com.tw/Products/tabid/58/ProdID/398/CatID/28/language/zh-TW/Default.aspx

Help?

DrPeter · Apr 17, 2017

Taking the compressor off seems like a whole nother level of difficulty, even loosening it from the bracket seems like it would be useless without removing the alternator, which seems too tight to get out without removing the intake. I'm at a loss.

- I found one here.

- Have you looked into dropping the engine a bit? I have done this while supporting the engine with a jack or engine hoist and then loosening the engine mount and slowly lowering the engine a just enough to do the work.

Be careful to only lower the engine as much as needed! Also properly (safely) secure the engine and vehicle!

Hope that helps too,

drpeter..

harr2969 · Apr 17, 2017

Thanks, but if you look closely you'll note those are internal ring removers, which work in the opposite direction when squeezed.

I have not yet considered dropping the engine engine a bit... Not sure if removing the alternator and maneuvering the compressor would be more or less work than that, but thanks for the idea.

harr2969 · Apr 18, 2017

Dropping that side of the engine was easier than I thought... two bolts and "boom". (Boom - in the non-dramatic, properly secured sense) Thank you very much Doc.

I did loosen the three bolts between the turbo and the downpipe to reduce the downpipe flex... not sure if that was absolutely needed, but it only took 5-10 mins since I had other stuff out so I thought it was worth it.

The clutch replacement happened pretty fast after that, and the A/C is working now, yay!

The fluid is slightly noisy, not a lot, but I'm not sure if it's due to a small bit of air or something else in the pipes... will continue to evaluate.

stamant · Aug 7, 2018

I also have a 2004 Audi Quattro TT 8N Roadster. I purchased the Ross-Tech Hex-V2 to help diagnose my AC that stopped working after the battery went dead. I did an auto scan, but it did not find any fault codes for the HVAC system. So decided to check the HVAC system block. The manual I have tells me how to use the Vag 1551 but for some reason I just cant find anywhere the procedure to use with the Hex-V2. It doesn't have the same functions. I've searched everywhere with no luck and looked in the Wiki for that model and its pretty vague. Any kind of help or get me pointed in the right direction would sure help. I emailed Ross-Tech support, but they never responded to my email. Thanks.

Andy · Aug 8, 2018

stamant said:
I emailed Ross-Tech support, but they never responded to my email. Thanks.

You emailed yesterday at 8:41pm (2h41m after we close) and then posted 23 minutes later saying we never responded to your email? :facepalm:

harr2969 · Aug 27, 2018

stamant said:
I also have a 2004 Audi Quattro TT 8N Roadster. I purchased the Ross-Tech Hex-V2 to help diagnose my AC that stopped working after the battery went dead. I did an auto scan, but it did not find any fault codes for the HVAC system. So decided to check the HVAC system block. The manual I have tells me how to use the Vag 1551 but for some reason I just cant find anywhere the procedure to use with the Hex-V2. It doesn't have the same functions. I've searched everywhere with no luck and looked in the Wiki for that model and its pretty vague. Any kind of help or get me pointed in the right direction would sure help. I emailed Ross-Tech support, but they never responded to my email. Thanks.

Did you figure this out? My a/c has been mostly working since the clutch replacement, but I am having a problem that it sporadically turns off and on at idle - no codes though, the computer still thinks it's on.

harr2969 · May 29, 2023

I did a quick google on the TT's a/c compressor clutch gap as I'm working on replacing the clutch for a second time (5 years later)... not OEM.

Funny enough to find my own thread. Since I didn't post the specific gap earlier, the ERWIN documentation says .4mm to .8mm. You need a depth gauge to accurately measure this style of clutch unfortunately, because there's no side access, only top access. Lowering the engine again is the best approach.

2004 Audi TT 225 roadster a/c clutch won't engage

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