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DIY CCU Repair

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MarkGolf
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MarkGolf PCGB Member
2021/03/24 12:43:13 (permalink)

DIY CCU Repair

Written by PCGB member Mark Sloane, his account on a DIY repair of his climate control unit. 
 
Climate Control Unit Repair.
 
For a long time I have been aware that my defrost slider did not direct air towards the windscreen. This wasn’t usually an issue as I try to only drive my car in the summer/dry weather.
 

 
Lockdown boredom generated time to investigate further and seek a solution. The obvious place to start was with the servo (located behind the fuel tank). There are 5 servos in total. The defrost servo is the first on the left. After supplying 12 volts to the servo I was able to confirm the servo works and the arm moves to open and close the flap. I then made some wires to connect the warm air servo connector to feed the defrost servo. I did this to see if adjusting the warm air signal from the ccu would open and close the defrost flap. It did. This also confirmed that the servo was not the issue and that the CCU was doing its job correctly for the warm air adjuster. The lazy option at this stage would be to disconnect the defrost servo in the open position which would allow air to the windscreen all the time. I’m not one for doing half a job so I soldiered on, keen to find the root cause. Further investigation also revealed that the servo for the footwell and the warm air mixer on the right were also not working. A reconditioned CCU can cost up to £600 so I was now at a point where I was very keen to fix it.
 
I turned my attention to the outputs from the CCU unit. I wanted to see if the CCU was providing the necessary voltage to drive each servo. Some quick continuity checks taught me which pins on the CCU connectors fed each servo. Using a multimeter I could see whether the correct voltage was going to each servo. As I slid the adjuster the footwell or the defrost I could see the output shot to overload. Further reading online suggested the power overload reading was due to the power op-amps being unable to maintain the required voltage to activate the servo.
 
I found some replacement op-amps online for £4 each so I thought I might as well replace all 4 to ensure I don’t have to repeat the job again in the near future. The components you need are Siemens TCA2465. (marked as IC9,10,11&12 on the pcb)
I soldered in the new op-amps without any issue and as soon as I plugged the CCU back into the connectors and turned on the ignition I could hear the servos moving to their correct locations.
 

 

 
So, after 8 years of procrastination, here is how long it took me to fix the issue:-
 
1 hour to confirm servo all servos operating correctly using remote 12volt supply where necessary.
2 hours – checking wiring and continuity.
2 hours - online research (looking for wiring diagrams and other useful hints)
1 hour - soldering in new op-amps.
5 minutes to pat myself on the back and put the plastic cover back over the servos!
 
Next job – Replace the recirculation button now that everyone in the club has seen a picture of how shabby looking it is!
 
Thanks to Mark for this and as in the picture, my CCU is the same, what is with the upside down icons?! What is the reason for this?
 
A picture of Marks beautiful 964
 

 
 

Current fleet
1991 964 Carrera
2005 997 Carrera S
2008 957 Cayenne GTS
2003 Boxster 2.7
1994 Eunos Roadster S Special Turbo 270bhp!
1991 Mercedes 500SL
1979 Mercedes 280e
1995 VW Golf VR6 3.0

11 Replies

deano911
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Re: DIY CCU Repair 2021/03/24 12:54:37 (permalink)
MarkGolf
Written by PCGB member Mark Sloane, his account on a DIY repair of his climate control unit. 
 
Climate Control Unit Repair.
 
For a long time I have been aware that my defrost slider did not direct air towards the windscreen. This wasn’t usually an issue as I try to only drive my car in the summer/dry weather.
 

 
Lockdown boredom generated time to investigate further and seek a solution. The obvious place to start was with the servo (located behind the fuel tank). There are 5 servos in total. The defrost servo is the first on the left. After supplying 12 volts to the servo I was able to confirm the servo works and the arm moves to open and close the flap. I then made some wires to connect the warm air servo connector to feed the defrost servo. I did this to see if adjusting the warm air signal from the ccu would open and close the defrost flap. It did. This also confirmed that the servo was not the issue and that the CCU was doing its job correctly for the warm air adjuster. The lazy option at this stage would be to disconnect the defrost servo in the open position which would allow air to the windscreen all the time. I’m not one for doing half a job so I soldiered on, keen to find the root cause. Further investigation also revealed that the servo for the footwell and the warm air mixer on the right were also not working. A reconditioned CCU can cost up to £600 so I was now at a point where I was very keen to fix it.
 
I turned my attention to the outputs from the CCU unit. I wanted to see if the CCU was providing the necessary voltage to drive each servo. Some quick continuity checks taught me which pins on the CCU connectors fed each servo. Using a multimeter I could see whether the correct voltage was going to each servo. As I slid the adjuster the footwell or the defrost I could see the output shot to overload. Further reading online suggested the power overload reading was due to the power op-amps being unable to maintain the required voltage to activate the servo.
 
I found some replacement op-amps online for £4 each so I thought I might as well replace all 4 to ensure I don’t have to repeat the job again in the near future. The components you need are Siemens TCA2465. (marked as IC9,10,11&12 on the pcb)
I soldered in the new op-amps without any issue and as soon as I plugged the CCU back into the connectors and turned on the ignition I could hear the servos moving to their correct locations.
 

 

 
So, after 8 years of procrastination, here is how long it took me to fix the issue:-
 
1 hour to confirm servo all servos operating correctly using remote 12volt supply where necessary.
2 hours – checking wiring and continuity.
2 hours - online research (looking for wiring diagrams and other useful hints)
1 hour - soldering in new op-amps.
5 minutes to pat myself on the back and put the plastic cover back over the servos!
 
Next job – Replace the recirculation button now that everyone in the club has seen a picture of how shabby looking it is!
 
Thanks to Mark for this and as in the picture, my CCU is the same, what is with the upside down icons?! What is the reason for this?
 
A picture of Marks beautiful 964
 

 
 


Great write up Mark, also have a 964 but touch wood I don't have any faults but if I so do I know how to sort hopefully.
Cheers
 
Dean
 
MarkGolf
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MarkGolf PCGB Member
Re: DIY CCU Repair 2021/03/24 13:37:31 (permalink)
Thanks Dean, Credit goes to Mark for sure on this. 
 
I sent my CCU off to BergvillFX but following this, may have made me attempt a DIY on it. 
 
 

Current fleet
1991 964 Carrera
2005 997 Carrera S
2008 957 Cayenne GTS
2003 Boxster 2.7
1994 Eunos Roadster S Special Turbo 270bhp!
1991 Mercedes 500SL
1979 Mercedes 280e
1995 VW Golf VR6 3.0
iangray100
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iangray100 PCGB Member
Re: DIY CCU Repair 2021/03/26 13:56:59 (permalink)
Years ago I did a transistor replacement fix to my CCU as it was faulty, but last year I sent the CCU off to Tore @ BergvillFX to update and check over as he fixes some of the weak design issues of the CCU in the process .
 
He has now had the obsolete buttons remanufactured to refurbish your CCU as new 😉  ....you can’t buy the buttons through you have to send them the CCU to replace the buttons ;-)
 
Or go cheap and buy his button stickers 😉

Ian
Coupe C2 964 MY92 Tiptronic (Engine rebuild featured in "Total 911" Jan 2008), Car on show at Autosport 2009.
Personal Engine rebuild thread: http://forums.pelicanparts.com/showthread.php?t=340187
iangray100
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Re: DIY CCU Repair 2021/03/26 14:12:33 (permalink)
The picture is quite small so wording is here.......
 
We are especially proud to announce that we now also stock the Double A/C switch used in the 993 CCU's. This switch has never before been available as a spare part.

We even offer a small twist to this: Along with the standard yellow lights, we also offer the A/C switches (both 964 and 993 types) with BLUE indicator lights, presenting a nice modern look to the unit.
 
These switches are not up for sale in our web shop, but only available in conjunction with our CCU service job. We fully test and refurbish these units, and deliver guaranteed results with our standard five year warranty. Our Repair Report comes with car work instructions if the cause for failure lies elsewhere in the car. We never leave a problem unsolved!

DHL Express round trip delivery
Due to Covid 19 delays in normal mail deliveries, we now offer DHL Express delivery for the delivery both to and from us. Delivery time is 1-3 days worldwide, so you can have a unit out and back in the car in a week. Normal one-way delivery price is EUR 20 to 35, (USD25-45) depending on location. Contact us for an offer.
 
www.bergvillfx.com
Tore is very helpfull
post edited by iangray100 - 2021/03/26 14:16:56

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Ian
Coupe C2 964 MY92 Tiptronic (Engine rebuild featured in "Total 911" Jan 2008), Car on show at Autosport 2009.
Personal Engine rebuild thread: http://forums.pelicanparts.com/showthread.php?t=340187
MoC2S
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Re: DIY CCU Repair 2021/03/26 20:58:58 (permalink)
Yes, perhaps Tore Bervill has insufficient credit here .. his DiY articles are a model for us all !!
 
cheers, Maurice

© Maurice Piper 2021 All Rights Reserved & No Licence Granted
993 Register Secretary 2003-2020
993 Assistant Register Secretary 2001-2003
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'Wild Things are always Faster'
mcgc0
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Re: DIY CCU Repair 2021/03/27 11:49:51 (permalink)
Yeah, my CCU was flakey to start with and now no longer functions. A Bergville revival is on my list but tbh, it not working hasn't been a showstopper for me - never needed to warm up the interior or demist the screen. However, I know it has other complicated functions which other engine components depend on - oil cooler temp signal inputs for low/high fan speed (not just the ballast resistor for this) and the rear blower fan etc.. Oil temp/cooling for me is excellent and never exceeds 10 o'clock pos even after tracking. Still, one day I'll get round to getting the CCU done and I'll be keeping an eye on this thread in the meantime.

'90 964 C4 Velvet Red
'94 968 Sport Gaurds Red
'90 964 C4 Slate Grey
'08 Golf Mk 5 GTi Black
iangray100
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Re: DIY CCU Repair 2021/03/30 09:42:36 (permalink)
mcgc0
Yeah, my CCU was flakey to start with and now no longer functions. A Bergville revival is on my list but tbh, it not working hasn't been a showstopper for me - never needed to warm up the interior or demist the screen. However, I know it has other complicated functions which other engine components depend on - oil cooler temp signal inputs for low/high fan speed (not just the ballast resistor for this) and the rear blower fan etc.. Oil temp/cooling for me is excellent and never exceeds 10 o'clock pos even after tracking. Still, one day I'll get round to getting the CCU done and I'll be keeping an eye on this thread in the meantime.




Interesting, my brain works in a different way ...if its not working I get the electronics fixed while someone in the world is able to do this work to a high standard and at a reasonable cost and it also comes with 5yrs warranty (the cost of the electronics from Porsche are silly money and their supply (recon or new) wont least for ever) .
 
It will only get more difficult to get our electronics fixed as they age and I'm seeing it already . My Spoiler controller failed last month by just powering up the spoiler when the car was all locked, a classic controller issue. I have one of Tore’s T-Spoiler controllers now and the old one is with him to be fixed as a backup.
 
I’ve been building up spares of all the 964 ECU/controllers over the years , as it will be the weak link in the future for our cars . The mechanical side is relatively easy to fix.  
 

Ian
Coupe C2 964 MY92 Tiptronic (Engine rebuild featured in "Total 911" Jan 2008), Car on show at Autosport 2009.
Personal Engine rebuild thread: http://forums.pelicanparts.com/showthread.php?t=340187
mcgc0
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Re: DIY CCU Repair 2021/03/31 17:14:10 (permalink)
iangray100
 
Interesting, my brain works in a different way ...if its not working I get the electronics fixed while someone in the world is able to do this work to a high standard and at a reasonable cost and it also comes with 5yrs warranty (the cost of the electronics from Porsche are silly money and their supply (recon or new) wont least for ever) .
 

 
That's not to say I don't want to, or won't get the CCU repaired (with Berg.), it's simply a case of definitely don't need the cabin heated, oil temp in the summer has never exceeded 9 o'clock pos and everything else is fine. It didn't make it to the top of my DIY repair list compared to replacing the long. diff lock slave, front drop links, new oil level sender and now replace the voltage regulator. Luckily I have access to an electronics whizzo with a 911 of his own who I can lean on if I needed.

'90 964 C4 Velvet Red
'94 968 Sport Gaurds Red
'90 964 C4 Slate Grey
'08 Golf Mk 5 GTi Black
Chrischitt
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Re: DIY CCU Repair 2022/05/04 12:21:33 (permalink)
Mark (or Mark?)
I have the same issues but cannot find the Op Amps anywhere in the UK - do you know of a source?
Thanks
Chris
iangray100
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Re: DIY CCU Repair 2022/05/04 13:47:53 (permalink)
I sent my CCU that was on the blink and the spoiler ECU that failed to www.bergvillfx.com & you get a guarantee as well , and he also upgrades the week points in the designs.
 
He also sells some of the components as well for DIY , his spoiler controller works very well as have the porsche one as  a spare in stock

Ian
Coupe C2 964 MY92 Tiptronic (Engine rebuild featured in "Total 911" Jan 2008), Car on show at Autosport 2009.
Personal Engine rebuild thread: http://forums.pelicanparts.com/showthread.php?t=340187
Chrischitt
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Chrischitt PCGB Member
Re: DIY CCU Repair 2022/05/04 16:30:55 (permalink)
Thanks Ian - I will contact Torre for a quote and also find out a bit more about these 'weak points' that Ive heard mentioned before.
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