B8.5 rear temperature flap positioning motor V137

[A4fuzz]

I've noticed my Auto HVAC blowing colder air than normal. I usually just leave it set at 68-70f but its been a little off lately. The ambient temps in Ohio have been in the 40's and 50's for perspective. I can't speak to AC / cooling performance yet.

A VCDS scan showed the following:

Address 08: Auto HVAC (J255) Labels:. 8Kx-820-043-3Z.clb
Part No SW: 8K1 820 043 AQ HW: 8K1 820 043 AQ
Component: KLIMA 3 ZONEN H04 0123
Revision: C1000000 Serial number: 01020920140584
Coding: 6480208000
Shop #: WSC 02391 785 00200
VCID: 77ABE8C5CFC4AEA23E9-8022

1 Fault Found:
01187 - Rear Temperature Flap Positioning Motor (V137)
002 - Lower Limit Exceeded - Intermittent
Freeze Frame:
Fault Status: 00100010
Fault Priority: 3
Fault Frequency: 1
Reset counter: 222
Mileage: 128243 km
Time Indication: 0
Date: 2023.03.26
Time: 16:42:44

Freeze Frame:
Voltage: 14.40 V
Temperature: 20.0°C
Temperature: 16.0°C
Count: 10000
Count: 9772
Bin. Bits: 01000000
Bin. Bits: 00000111
Time: 255.00 s

This error comes back after clearing and running through the function tests in VCDS again. I believe the temperature flaps are on the driver side but can anyone confirm this? Seems like it should be an easy fix as long as this particular motor is accessible. Does anyone have any experience or input on this fix?

[Smac770]

There's three temp doors on the 3-zone climate system, as there are three temp controls in the system: front left, front right, and rear. So that's an error about the motor that moves the temp door for the rear. No reason for it to influence results for the front seats.

[A4fuzz]

I can't find a diagram for the location and function of the various control motors. It's hard to explain the "difference" that i've noticed recently but it could be that its blowing cold air out the rear vents, throwing off my "auto" temperature. I'll start with this motor and see what happens.

[Smac770]

That would be in the HVAC workshop manual. General air flow in the cabin is in the front and out the rear. I doubt those small rear vents are making that much impact up front; the interior temp sensor is above the driver's right knee, on the underside of the dash. I'd start by monitoring the measuring blocks showing the output temp sensors (there's a temp sensor in the output ducts so the control module knows what air temp is going out to the cabin), and monitor that as you change the three different temp selectors. See if things are tracking correctly, etc.

I rarely have the AC on. With the HVAC on, even with the temps in the 40s this weekend here in GA, I've not made any change to my normal set temp of 72 (I like to pop the sunroof, even if it's chilly out).

[A4fuzz]

I did as you suggested and purchased / downloaded everything on the erWin site for my VIN. The one thing that erWin seems to be missing is diagnostic procedures. The service manual just keeps referring you back to the Vehicle Diagnostic Tester in the "Guided Fault Finding" function, which is a function of ODIS apparently. That being said, its still a worthwhile investment and answered the question of where these motors were. For anyone wondering they are all on the drivers side and luckily the one I will be replacing is the bottom one with fairly easy access. The other motors could prove to be difficult without more disassembly. I'll report back when I get the new one shipped and installed in a few days.

It looks like the only thing to do in VCDS is the "basic settings" in the HVAC module - potentiometer and flap alignment. If all goes well it runs the flaps back and forth and I should be error free and have heat in the back seats.

[Smac770]

"missing is diagnostic procedures", yeah, and it's only gotten worse over time. RGFF is basically Audi code for pay us for ODIS or FOAD.

[A4fuzz]

I replaced the motor with relative ease. I'm having trouble getting VCDS to perform basic settings now that it is replaced. It seems to be working as I can see it moving back and forth with input from the control unit but now I have the "basic settings not performed" error and something about no communication. When I go into the 08-Auto HVAC module and click on basic settings, it lets me select flap alignment but when I click "start" it says "aborted" after about a second. The flaps still move around but it doesn't save anything apparently. I can't figure this out. I've done it with the car on and off / HVAC on and off / HVAC on hi / lo. I've tried all combinations and it just aborts the basic settings right away. What am I doing wrong?

[Smac770]

When we normally see the LIN bus in the vehicle, we see it as a wire that forks and runs directly to each device. So a tree look. The HVAC motors are also managed by LIN bus, but instead it's a daisy chain pass through configuration, more akin to Flexray layout.

"something about no communication", so complete scan log content would be more interesting here, or at least the section for 08-auto hvac.

Unfortunately, the error feedback in the basic settings interface is somewhere between non-existent and useless junk.

The workshop manual refers to "Using the functions “Output diagnostic test mode“ and “Basic setting“, the activation of A/C system electrical components can be tested if necessary". The basic setting part, expected. Not sure what is meant by output diagnostic test mode. Not sure if that's excessive translation of output tests. This is not an operation I've had to do personally, I've been ignoring the DTC for one of my flap motors for a long time.

https://youtu.be/yFnq3lbaBVI?t=621
So here we see the "instructions" information in ODIS that Ross-Tech doesn't provide in VCDS. This wasn't so much an issue in old KW days, but it's a problem to not have the instructions of how to get things accomplished in modern days. It mentions needing to run 044 after a motor replacement before you can run 001. But then he scrolls down and it says 004 instead of 044. Suspect the 044 is a typo.

Have you tried basic setting 004? If that's giving an error, then would seem to be something up with the wiring or the units in the chain. If 004 works, then run 001.

[A4fuzz]

SOLVED!

Smac, I actually found that video right after I posted this. After watching the relevant part a few times I did exactly what you just said. So for future reference for anyone replacing a flap motor, there are three options on VCDS. First perform the basic settings in 004 to tell the module where the motor is in the line (its the option at the bottom of the list of the three known settings). This takes a few seconds. After that is complete then you can perform the basic settings in 001 for flap alignment which takes a few seconds as well.

Thanks for working through this with me Smac haha... I am now error free in the HVAC module.