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Discussion Starter #1
Hi,
I have a 2008 T5 1.9 with BRR engine code and factory fit manual aircon which is not working. When I plug in VCDS I am unable to enter 08 HVAC to check for any faults it just pops up no response from controller, firstly is there anyone out there with a similar van, year and engine code that could check if they can get into 08 HVAC I am sure I have read somewhere that HVAC is only accessible if you have climatic controls but if someone else could check and confirm that would be great, if I should be able to get into it then that could be my aircon problem secondly where is the controller is it in the ECU, the comfort controller or the central controller or somewhere else?
This is now driving me crazy and any help would be great many thanks Barry.:*
 

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Discussion Starter #3
many thanks do you know how I find the problem then do I use measuring blocks in the engine ECU and if so do you know which they are, I can make the aircon work by going into engine ecu out put test?
Thanks Barry.
 

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I can make the aircon work by going into engine ecu out put test ? So can we !!


We have just been looking at mine as we have the same issue . The compressor can be made to kick in using VCDS but despite changing fan controller , high pressure switch and having the system re gassed twice it will not run .

The cooling fan will not run and we think this is a clue ? Then to cap it all running it up again using VCDS it decided to vent the gas via the high pressure relief valve under the bonnet .

Faulty Compressor ? But why would it run using vcds ?
 

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Current progess.
Blowing warm air all the time - even on the motorway.
VCDS reports no fault codes.
VCDS HVAC Output tests all work ok. You can hear compressor click when testing it via VCDS.
VCDS can run fans.
It has been regassed - pressure balance is even.
New Low Presure switch
New High Presure switch
Coupling to compressor looks ok & VCDS confirms it is rotating.
Engine bay fans have started running at a low speed - nothing line they use to run when turning on the aircon.
Bosch diagnostic tool shows 0 torque on the compressor as if it is not being activated.
Both pipes AC pipes in engine bay are warm - not cold at all.

Found this old post , sadly no answer or solution :*

Any one help ?
 

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Discussion Starter #6
Hi it's sort of reassuring to hear someone has the same problem
didn't know there was a low pressure sensor where is it?
I have changed the relay, high pressure sensor and the evaporator sensor
all to no avail I have now been te to look at switch by an independent VW garage but
I am not convinced but now clutching at straws will have a look
Let me know if you have any joy and I will keep you posted too.
Cheers Barry
 

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Discussion Starter #8
I have checked the switch today all seems to work ok so still no further forward can't believe it's so complicated everything appears to be working just not getting that final signal from the ecu to fire up the relay?
Barry:*:confused:
 

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I tried my fans tonight by disconnecting the wiring under the drivers headlight , perfect ! I have reason to suspect the compressor is to blame despite being able to run it up using vcds ? I read a post on the net today where a guy had gone to his local dealer handed over £1,000 ish for a new compressor fitted , was then demonstrated that it works with the computer [vcds] and the dealer wanted another small fortune to continue looking for the problem . So that may blow that theory out of the window ? Trail then went dead .

Certainly a strange one . keep me posted if i come up with anything i will get back to you , any one else help ?

Cheers
 

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Discussion Starter #11
I think this could be the ecu not recognizing that a/c is there more I read on the net there is a coding in the ecu to switch a/c on or off but I don't know where to find it or what the coding should be can anyone help?
Regards Barry
 

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I had the opposite which was the light did not come on and turned out to be the control module. Have you checked the CAN gateway to ensure that the HVAC unit is enabled. Also within the engine module you'll find reference to whether climate control is enabled or not.
 

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Discussion Starter #15
Firstly I don't have climate control just manual a/c so no hvac not sure how to check can gateway or the ecu coding for a/c
 

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Are you sure you are using the right names? As I understand it, climatic aircon is the "entry level" version, which my van has (and it sounds like yours does). Mine is visible within VCDS as 08 HVAC, and is coded as follows:

Address 08: Auto HVAC (J301) Labels: 7E5-907-047.clb
Part No SW: 7E5 907 047 BM HW: 7E5 907 047 BM
Component: Climatic-T5 H20 0505
Revision: 00001010
Coding: 0000000002
Shop #: WSC 02756 790 50316
ASAM Dataset: EV_ClimaticT5 A01003
ROD: EV_ClimaT5Basis_VN75.rod
VCID: 7BF518A6F2F4EBE220-802E

[Edit: but I should add that mine is a facelift, so perhaps that doesn't help much...]
 

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many thanks BarryT:
Hi Barry,

Did you ever sort this issue? I have a 2007 1.9 102bhp T5. When I switch on the aircon the light goes on but nothing happens. System is gased up and tested today but still no joy. VCDS lite can only access the engine and airbags... HVAC returns "no responce from controller". The compressor clutch doesn't engage when the aircon is switched on. I have 12.7 volts across the compressor connector (whether AC is switched on or off). I have just purchased a relay (7E0919506) from fleabay... The main dealer wanted £150... but really not sure this is going to fix my issue.

Is VCDS supposed to read the HVAC as I've heard it shouldn't necessarily? Any help with this repair would be apprieciated.

Cheers Chris
 
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