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Post by guy508 on Aug 30, 2021 5:50:56 GMT
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Post by dv52 (Australia) on Aug 31, 2021 23:08:36 GMT
First-off, I'm not an air compressor expert- so what you are about to read is simply my understanding of how VW air-con systems operate and I'm guessing that this applies to your ID.4 vehicle.
So, with caveat above as context, the air-con in modern VAG cars no longer use the traditional constant-displacement compressors - in which the compressor output was modulated for changing temperature demand by switching the compressor on/off periodically via a magnetic clutch. Instead, modern compressors use what's called a "Wobbleplate" compressor in which the turning motion of the shaft is converted to a back-and-forth motion (= piston stroke) by means of a wobbleplate like this:
Hopefully you can see how the circular motion of the wobbleplate is translated to axial motion in the picture. Now, the picture shows 3 x pistons, but depending on compressor type, this can vary. Hopefully also you can see how the length of the piston stroke (and therefore the compressor delivery-rate) can be changed by the angle of the wobbleplate. These type of compressors run continuously when the car is in air-con mode. In terms of how your changes work, I'm aware that wobbleplate compressors on MQB platform cars have 2 x design states (called "high cooling capacity" and "low cooling capacity", but on MQB cars VAG uses more PC terms like "hot-country" and "normal") - I suspect that these operating states are used for the emission standards in some countries. The way that these modes are selected is via a "regulating valve" which is shown below on the control-mechanism version of my first picture
When high capacity is selected, the operation of the "regulating valve" in the compressor is altered. The opening of this valve causes (mostly?) the high pressure refrigerant gases to take a different route inside the compressor and the end result is that the stroke of the wobble-plate compressor is increased. In "low" cooling mode, the different regulating valve position results in a short stroke for compressor operation.
I stress that changing between high and low capacity modes is not like overclocking a CPU - these are normal operating states that have been designed into the compressor. My suspicion (guess really) is that your tweak results in selecting the high capacity mode on the compressor - which is designed for cars that are sold in "hot countries".
Don
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Post by guy508 on Sept 1, 2021 4:31:25 GMT
Thanks so much for your very detailed explanation. I’m surprised living in Phoenix this option wasn’t activated. It makes a huge difference. Is there some kind of documentation that can be referred to that details each of these options that are available via obd11.
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Post by dv52 (Australia) on Sept 1, 2021 4:56:47 GMT
guy508 : AFAIK, there is nothing in the public domain that explains how settings like those in your pictures are meant to work - but I'm more than happy to be told otherwise by anyone here. And, my diatribe is nothing more than speculation (again, happy to be proven wrong if anyone knows otherwise) As I said, my hunch (guess really) is that the factory settings that are delivered with the car have a relationship to the emission standards that are imposed by the country of sale. I've not been to Phoenix, so I'm not aware of your summertime climate- but Yankee emission standards for cars are tough, so maybe this explains why VW America has compromised cabin cooling performance to allow the ID.4 to be sold in Phoenix (perhaps?). Here in Australia where it is quite warmish in summer and the emission standards are arguably not so tough - the "hot country" settings are factory set on our cars. Also, I sense an emphasis in your reply that these options are somehow OBD11 related. The truth is that the settings in your pictures are inherent in the HV AC module that lives @ address hex08 on the CAN Network. So it doesn't matter what diagnostic cable is used to make these changes. OBD11 is simply reading the software switches in the module and presenting them to the user in a fancy GUI! Don
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Post by guy508 on Sept 1, 2021 6:34:13 GMT
Thanks for the update. And yes I am aware these options are VW, not obd11. My question is are these various VW options and explanations available anywhere, some kind of guide or manual?
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Post by Deleted on Sept 1, 2021 11:46:45 GMT
guy508 I am afraid there is no Guide other than the information that Good people share for free. VW Obviously have user manuals but these are in my view very generic so would not talk about all the features a car may have but they do offer ERWIN which gives much more technical detail check out forums.ross-tech.com/index.php?threads/5999/ but this does not talk about what you can code on the vehicle just how it all works in detail.
OBD11 Do provide a Help system but to be fair again this is very high level and generic and is about how to use the app not how to do stuff to your car. Bottom line best place to find out about these Features is search VW ID Forums and keep an eye out on other VAG Models that may share the same underpinnings. Last bit of information is that your car will be protected from changes by vw SFD Security which limits what control units you can adapt, vs older cars.
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Post by guy508 on Sept 1, 2021 16:35:17 GMT
Many thanks to you all for providing all the info to this lay person
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