MarkGolfWritten 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
mcgc0Yeah, 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.
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) .
Posts made and opinions expressed are those of the individual forum members Use of the Forum is subject to the Terms and Conditions
Disclaimer
The opinions expressed on this site are not necessarily those of the Club, who shall have no liability in respect of them or the accuracy of the content. The Club assumes no responsibility for any effects arising from errors or omissions.
Porsche Club Great Britain gives no warranties, guarantees or assurances and makes no representations or recommendations regarding any goods or services advertised on this site. It is the responsibility of visitors to satisfy themselves that goods and/or services supplied by any advertiser are bona fide and in no instance can the Porsche Club Great Britain be held responsible.
When responding to advertisements please ensure that you satisfy yourself of any applicable call charges on numbers not prefixed by usual "landline" STD Codes. Information can be obtained from the operator or the white pages. Before giving out ANY information regarding cars, or any other items for sale, please satisfy yourself that any potential purchaser is bona fide.
Directors of the Board of Porsche Club GB, Club Office Staff, Register Secretaries and Regional Organisers are often requested by Club members to provide information on matters connected with their cars and other matters referred to in the Club Rules. Such information, advice and assistance provided by such persons is given in good faith and is based on the personal experience and knowledge of the individual concerned.
Neither Porsche Club GB, nor any of the aforementioned, shall be under any liability in respect of any such information, advice or assistance given to members. Members are advised to consult qualified specialists for information, advice and assistance on matters connected with their cars at all times.