Webasto Auxiliary Heater & Air Blower strange behavior (VW T6)

[SMS]

Hello everyone,


I’m having an issue with the ventilation system on my vehicle (T6) The air does not blow, but I can hear the mechanisms reacting when I change the settings. The resistor has already been replaced, but it didn’t solve the problem, fuses seems to be ok, but I'm unable to find the hot air blower fuse (40a) that is under the light switch driver side ???


Additionally, the vehicle is equipped with an auxiliary webasto heater, which starts up but does not blow air either.


Has anyone experienced a similar issue? Any ideas on what could be causing this?


Thanks in advance for your help!

 

[SMS]

Hi everyone,

(sorry for the double post, please modo delete this one - ty)

I’m having an issue with my Webasto Thermo Top Evo auxiliary heater and the fresh air blower on my VW Transporter T6. In parking mode, the heater works, but as soon as I insert the key, the blower starts working while the heater keeps heating… - is this the normal behaviour ?

Additionally, the fresh air blower doesn’t work when the key is on in normal driving mode –

I also have no AC. I can hear the mechanisms reacting when I change the settings, but there’s no airflow. The resistor has already been replaced, but that didn’t solve the problem. The fuses seem to be fine.

That being said, the air blower also works when tested with VCDS.

Worth mentioning:

I previously had an issue with the key (it's my only key, I don’t have a spare) and had to reprogram it after replacing the battery.
The heater is powered by the battery located under the seat.
Has anyone experienced this strange behavior before? Could it be related to this freaking key? Any help would be greatly appreciated!

Thanks in advance!

Saturday,22,March,2025,19:18:04:12236
VCDS -- Windows Based VAG/VAS Emulator Running on Windows 11 x64
VCDS Version: 25.3.0.4 (x64) HEX-V2 CB: 0.4660.4
Data version: 20250311 DS365.0
www.Ross-Tech.com


VIN: WV1ZZZ7HZGH121311 License Plate:
Mileage: 268180km-166639mi Repair Order:



--------------------------------------------------------------------------------
--------------------------------------------------------------------------------


Chassis Type: 7H-VN75 (7E0)
Scan: 01 03 04 08 09 10 13 15 17 18 19 22 25 5F 61 69 6E 0B

VIN: WV1ZZZ7HZGH121311 Mileage: 268180km-166639miles

01-Engine -- Status: OK 0000
03-ABS Brakes -- Status: OK 0000
04-Steering Angle -- Status: OK 0000
08-Auto HVAC -- Status: OK 0000
09-Cent. Elect. -- Status: OK 0000
10-Park/Steer Assist -- Status: OK 0000
13-Auto Dist. Reg -- Status: OK 0000
15-Airbags -- Status: OK 0000
17-Instruments -- Status: OK 0000
18-Aux. Heat -- Status: Malfunction 0010
19-CAN Gateway -- Status: OK 0000
22-AWD -- Status: OK 0000
25-Immobilizer -- Status: OK 0000
5F-Information Electr. -- Status: Malfunction 0010
61-Battery Regul. -- Status: Malfunction 0010
69-Trailer -- Status: OK 0000
6E-Ctrl Head Roof -- Status: OK 0000
-------------------------------------------------------------------------------
Address 01: Engine (2D2D2-CXHA) Labels:. 04L-907-309-V2.clb
Part No SW: 04L 906 056 KK HW: 04L 907 445
Component: R4 2.0l TDI H02 3803
Revision: 23002001
Coding: 0019401C433601090000
Shop #: WSC 27577 001 1048576
ASAM Dataset: EV_ECM20TDI03004L906056KK 004005
ROD: EV_ECM20TDI03004L906056JT.rod
VCID: 005996365A81FFCA8F7-8054
VINID: 9E606AAAA1D8A976010810C1047F8B6DA9

No fault code found.
Readiness: N/A

-------------------------------------------------------------------------------
Address 03: ABS Brakes (J104) Labels: 7E0-907-37x-MK100ESC.clb
Part No SW: 7E0 907 379 P HW: 7E0 907 379 M
Component: ESC H05 0132
Revision: 00000000 Serial number: 40676000001447
Coding: 557EC0982564847FAA780377A48321A678F100
Shop #: WSC 02739 790 50316
ASAM Dataset: EV_Brake1ESCCONTIVN75XGP2 011001
ROD: EV_Brake1ESCCONTIVN75XGP2_011.rod
VCID: 3FDB55CA67FF4032B6D-806A

No fault code found.

-------------------------------------------------------------------------------
Address 04: Steering Angle (G085) Labels:* 6R0-959-654.clb
Part No SW: 6R0 959 654 HW: 6R0 959 654
Component: LENKW.SENSOR H07 0070
Serial number: 26011613470678
Coding: 01
Shop #: WSC 00000 000 00000
ASAM Dataset: EV_LWSKLOVW25X 005001
ROD: EV_LWSKLOVW25X.rod
VCID: 7EA5E8CE2075893AFDB-802A

No fault code found.

-------------------------------------------------------------------------------
Address 08: Auto HVAC (J301) Labels:| 7E5-907-047.clb
Part No SW: 7E0 907 047 AK HW: 7E0 907 047 AK
Component: Climatic-T5 H22 0708
Revision: 00001002
Coding: 0000000003
Shop #: WSC 02737 790 50316
ASAM Dataset: EV_ClimaticT5 A01003
ROD: EV_ClimaT5Basis_VN75.rod
VCID: 73B3C9FA1B37D452825-8026

No fault code found.

-------------------------------------------------------------------------------
Address 09: Cent. Elect. (J519) Labels:. 7E0-937-BCM-V1.clb
Part No SW: 7E0 937 090 HW: 7E0 937 090
Component: BCM PQ25 Max4 H80 0736
Revision: B9080001 Serial number: 0771 070160628
Coding: 22A0303A0A6134B393284F747CEB8E748FB4688F60CC6960320400A20840
Shop #: WSC 02737 534 205768
VCID: 6889AE965271278A277-803C

Subsystem 1 - Part No: 5K7 955 559 B Labels: 5K7-955-559.CLB
Component: RLS 090316 03 37 0059
Coding: 0228EE

Subsystem 2 - Part No SW: 7E0 959 801 H HW: 7E0 959 801 H Labels: 7E0-959-80X-V2.CLB
Component: J386__TSG_FT 003 8654
Serial number: KU0KU016031660763825
Coding: 0400A0

Subsystem 3 - Part No SW: 7E0 959 802 H HW: 7E0 959 802 H Labels: 7E0-959-80X-V2.CLB
Component: J387__TSG_BT 003 8654
Serial number: KU0KU016031660767288
Coding: 1400A0

Subsystem 4 - Part No: 7E1 951 172
Component: DWA-Sensor 00 001 0104
Coding: 000000

Subsystem 5 - Part No: 1K0 951 605 C
Component: LIN BACKUP HO H05 1501
Coding: 000000

Subsystem 6 - Part No: 7E1 951 172
Component: DWA-Sensor 00 001 0104
Coding: 000000

Subsystem 7 - Part No SW: 7E0 959 442 HW: 7E0 959 442 Labels: 3C8-959-537.CLB
Component: E221__MFL-DC1 H02 0103
Serial number: 29160000450700056091
Coding: B0FFFF

No fault code found.

-------------------------------------------------------------------------------
Address 10: Park/Steer Assist (J446) Labels:| 7E0-919-475.clb
Part No SW: 7E0 919 475 R HW: 1Q0 919 475
Component: PARKHILFE 4K H03 0210
Revision: -------- Serial number: 32931602506373
Coding: 11800A
Shop #: WSC 02737 790 50316
ASAM Dataset: EV_VW75XParkAssis4K 001012
ROD: EV_VW75XParkAssis4K_001_VN75.rod
VCID: 41DF5332110B36C2C09-8014

No fault code found.

-------------------------------------------------------------------------------
Address 13: Auto Dist. Reg (J428) Labels:| 7N0-907-572.clb
Part No SW: 7N0 907 572 A HW: 7E0 907 572
Component: ACC Bosch PQx H03 0110
Serial number: 14031677110885 Dataset Number: 7E0114v____ 0009
Coding: 00004000FE0779
Shop #: WSC 01383 790 50316
ASAM Dataset: EV_ACCBEGVW361 001004
ROD: EV_ACCBEGVW361.rod
VCID: 34310AE65EB9936A5BF-8060

2 Faults Found:
1540 - Sensor for Automatic Distance Regulation; Incorrectly Positioned
C1103 00 [00001001] - -
[FAULT_MISALIGNMENT_HORIZONTAL]
Confirmed - Tested Since Memory Clear
Freeze Frame:
Fault Priority: 2
Fault Frequency: 1
Reset counter: 40
Mileage: 268137 km
Date: 2025.03.15.
Time: 11:14:27

Control Module temperature: 15 C
Voltage terminal 15: 12.2 V
Vehicle speed: 0.00 m/s
Acceleration: 0.00 m/s

1541 - Sensor for Automatic Distance Regulation; Incorrectly Positioned
C1103 00 [00001001] - -
[FAULT_MISALIGNMENT_VERTICAL]
Confirmed - Tested Since Memory Clear
Freeze Frame:
Fault Priority: 2
Fault Frequency: 1
Reset counter: 40
Mileage: 268137 km
Date: 2025.03.15.
Time: 11:14:27

Control Module temperature: 15 C
Voltage terminal 15: 12.2 V
Vehicle speed: 0.00 m/s
Acceleration: 0.00 m/s


-------------------------------------------------------------------------------
Address 15: Airbags (J234) Labels:| 5K0-959-655.clb
Part No SW: 7E0 959 655 G HW: 7E0 959 655 G
Component: VW10Airbag01L H08 0018
Revision: -------- Serial number: 003V300078EN Dataset Number: 7E0003V____ 0841
Coding: 00000000000000000000000000000000314C
Shop #: WSC 02734 790 50316
ASAM Dataset: EV_AirbaVW10BPAVW12X 001028
ROD: EV_AirbaVW10BPAVN750.rod
VCID: 3A2D24DE7CDD651A813-806E

No fault code found.

-------------------------------------------------------------------------------
Address 17: Instruments (J285) Labels:| 5K0-920-xxx-17.clb-SRI1
Part No SW: 7E0 920 870 L HW: 7E0 920 870 L
Component: KOMBI H05 1008
Serial number: 00000000000000
Coding: 160B010300
Shop #: WSC 02737 790 50316
ASAM Dataset: EV_Kombi_UDS_VDD_RM09 A05730
ROD: EV_Kombi_UDS_VDD_RM09_005_VW32.rod
VCID: 323D0CFEA4AD9D5A493-8066

No fault code found.

-------------------------------------------------------------------------------
Address 18: Aux. Heat (J364) Labels:| 7E0-963-27X-18.clb
Part No SW: 7E0 963 272 B HW: 7E0 963 272 B
Component: STH-T5GP2 003 0009
Coding: 4C01
Shop #: WSC 02737 790 50316
ASAM Dataset: EV_AuxilParkiHeateWOST5G2 001013
ROD: EV_AuxilParkiHeateWOST5G2.rod
VCID: 2B03119A8387CC920A5-807E

1 Fault Found:
0353 - Comfort System CAN Bus (SAE Medium Speed Bus)
U0011 00 [00001000] - Performance
[CAN KOMFORT GLOBAL TIMEOUT]
Intermittent - Confirmed - Tested Since Memory Clear
Freeze Frame:
Fault Priority: 6
Fault Frequency: 2
Reset counter: 85
Mileage: 268188 km

Parking heater: operating condition: OFF
71
Coolant temperature of parking heater: 15 C
Coolant temperature: -48 C
Engine running status: not detected
Fuel level: 29 l
Heating performance: 0 W


-------------------------------------------------------------------------------
Address 19: CAN Gateway (J533) Labels:. 7E0-909-901.clb
Part No SW: 7E0 909 901 HW: 7E0 937 090
Component: GW-K-CAN TP20 H80 0736
Revision: B9080001
Coding: 042207
Shop #: WSC 02737 534 205768
VCID: 6889AE965271278A277-803C

No fault code found.

-------------------------------------------------------------------------------
Address 22: AWD (J492) Labels:| 0CQ-907-554-V1.clb
Part No SW: 0AY 907 554 L HW: 0CQ 525 130 A
Component: Haldex4Motion H53 7620
Serial number: HA1-00019.06.19 Dataset Number: v1260x015G0 0000
Coding: 3807
Shop #: WSC 99999 999 83333
ASAM Dataset: EV_AllWheelContrHA1VW37X 002015
ROD: EV_AllWheelContrHA1VW37X_002_VW36.rod
VCID: 54F16A66FE79B36A7BF-8000

No fault code found.

-------------------------------------------------------------------------------
Address 25: Immobilizer (J334) Labels:| 5K0-920-xxx-25.clb
Part No SW: 5K0 953 234 HW: 5K0 953 234
Component: IMMO H05 1008
Serial number:
Coding: 000000
Shop #: WSC 00000 000 00000
ASAM Dataset: EV_Immo_UDS_VDD_RM09 A03710
ROD: EV_Immo_UDS_VDD_RM09_VW32.rod
VCID: 6A8DD49E4CFD159A313-803E

No fault code found.

-------------------------------------------------------------------------------
Address 5F: Information Electr. (J794) Labels:| 5G0-035-MIB-STD2.clb
Part No SW: 5C0 035 680 C HW: 5C0 035 680 C
Component: MU-S-ND-ER H22 0245
Serial number: VWZAZ2S8310028 Dataset Number: V03935240VJ 0001
Coding: 065700013C00000011111101008808001F0100C4002001004F
Shop #: WSC 131071 1023 2097151
ASAM Dataset: EV_MUStd4CTSAT 001022
ROD: EV_MUStd4CTSAT_VW32.rod
VCID: 211FF3B2F14B16C2A09-8074

Data carrier:
Subsystem 1 - Part No SW: V03 959 821 FN HW: -----------
Component: ECE DL2 24/25 --- 2210
Serial number: --------------------

1 Fault Found:
2562 - Navigation System
B126C F0 [00001000] - Navigation Database Faulty
Intermittent - Confirmed - Tested Since Memory Clear
Freeze Frame:
Fault Priority: 6
Fault Frequency: 1
Reset counter: 83
Mileage: 268168 km
Date: 2025.03.19.
Time: 16:44:10

Voltage terminal 30: 12.7 V


-------------------------------------------------------------------------------
Address 61: Battery Regul. (J840) Labels:. 1K0-907-534.clb
Part No SW: 7E0 907 534 HW: 7E0 937 090
Component: Batt.regelung H80 0736
Serial number: 0771 070160628
Coding: 330B1A73
Shop #: WSC 02739 790 00000
VCID: 6889AE965271278A277-803C

Subsystem 1 - Part No SW: 7E0 915 181 G HW: 7E0 915 181 G
Component: J367-BDM H08 0223
Serial number: 63062N24031261673606

1 Fault Found:
02256 - Quiescent Current
001 - Upper Limit Exceeded - Intermittent
Freeze Frame:
Fault Status: 00100001
Fault Priority: 7
Fault Frequency: 4
Reset counter: 85
Mileage: 268151 km
Time Indication: 0
Date: 2019.08.06.
Time: 22:59:46


-------------------------------------------------------------------------------
Address 69: Trailer (J345) Labels:. 1K0-907-383-V2.clb
Part No SW: 1K0 907 383 H HW: 1K0 907 383 G
Component: Anhaenger H12 0130
Revision: 3B001001 Serial number: 00000397787520
Coding: 410D000103000000
Shop #: WSC 27577 001 1048576
VCID: 323D0CFEA42D9D5A493-8066

No fault code found.

-------------------------------------------------------------------------------
Address 6E: Ctrl Head Roof (J702) Labels:. 7E5-919-037-W2.clb
Part No SW: 7E5 919 037 G HW: 7E5 919 037 G
Component: Dachdisplay H15 0185
Revision: 10100011 Serial number: 421888
Coding: 000102
Shop #: WSC 02759 790 00000
VCID: 353737E255438A626C1-8060

No fault code found.

End----(Elapsed Time: 02:01, VBatt start/end: 12.0V/12.0V. VIgn 12.0V)-----
------------------------------5 Faults Found-------------------------------

 

[mmi]

as soon as I insert the key, the blower starts???? working while the heater keeps heating

I guess you mean "stops working" as in the video??

I'm unable to find the hot air blower fuse (40a)

In parking mode, the heater works, but as soon as I insert the key, the blower starts???? working while the heater keeps heating

Aux heater runs cabin heater blower independently - bypassing normal circuitry. When ignition is turned on normal circuitry - including the missing fuse - takes over.

You definitely need to find/check the missing heater blower fuse first!

 

[SMS]

Hello @mmi thank you for your response, I saw your posts about VW auxiliary heaters here and on the Ross-Tech forums, and you seem very knowledgeable on the subject

Indeed thank you for correcting - the key stops blowing the air of the heater but the heater continues to heat - this is very dangerous

Like you can see in the first picture I'm unable to find that fuse, it's not in the default location

I read the PDF (SSP 416) that you have posted in your thread. Can you confirm that the two relays (J8 and J708) are not present in vehicles with AC?

Could this part 7H0 919 506 A been involved ?

Thanks in advance for your time.

 

[mmi]

I read the PDF (SSP 416) that you have posted in your thread.

Not accurate for T6 as not about Thermo Top Evo.

Could this part 7H0 919 506 A been involved ?

Why are you asking - isn't this radiator fan relay for 2005 T5??? No such a thing on T6?

Can you confirm that the two relays (J8 and J708) are not present in vehicles with AC?

Why are you asking?
They are present on your T6.
J8 runs the cabin heater blower when aux heater is on - as in your video.
J708 runs aux heater's coolant circulation pump

Like you can see in the first picture I'm unable to find that fuse, it's not in the default location

Well, it's providing power to your cabin heater blower... perhaps it has been tucked behind glove compartment as the wire should meet there connector T17a pin 1 (black/blue wire connects to red/yellow wire at the connector)

 

[SMS]

Thank you for your reply.

I have been looking everywhere, this is very very strange, I'm unable to find that fuse.




Is what one of this connectors that the cable should meet ?

 

[mmi]

The power supplying wire for the blower should meet black 17-pin connector (T17a pin 1) behind glove box.

Follow black wire (4 mm²) from motor to black 2-pin connector by the motor - wherefrom it continues as brown wire (4 mm²) to the above mentioned black 17-pin connector (T17a pin 2)

 

[SMS]

sry but I don't see what black connector. When I follow the brown 4mm2 it goes under the dashboard.

 

[SMS]

Anyway, as you can see in this video, I’ve checked again to be sure, and there is no cable for the S25 fuse where it’s supposed to be.

I’ll remove the fresh air control unit, but I don’t think I’ll find a fuse there. This is very strange.

 

[mmi]

sry but I don't see what black connector. When I follow the brown 4mm2 it goes under the dashboard.

Approximately in the boxed area - but behind the bar - high up. There should be a bracket which holds the 17-pin connector.

 

[SMS]

hi, you mean this connector ?

 

[mmi]

I believe so.

You do have wiring diagrams of your van?

I'm unable to find the hot air blower fuse (40a) that is under the light switch driver side ???

Actually your van quite possibly does not have that!

---
Anyways, before trying to access the 17-pin connector -

(1) Please check fuses SC1 (40A) and SC28 (5A)

(2) Please check that you have +12V at relay J493 (the relay "645" in the picture) pins 1 and 3 - when ignition ON.

(3) Does the relay click when igntion is turned on - then +12V should be also on pin 5 (connecting to T17a pin 1 and further to Climatic AC running the blower).

---

Auxiliary Coolant Heater Wiring Diagram

12 Jul 2021

Current flow diagrams

• Pauly
• auxiliary heater coolant heater
• VW T6 Electrical Info

Climatic Air Conditioning Wiring Diagrams

17 May 2020

Current flow diagrams

• Pauly
• air conditioning circuit diagram climatic current flow diagram hvac transporter t6 vw t6 wiring diagram
• VW T6 Electrical Info

 

[SMS]

(1) Please check fuses SC1 (40A) and SC28 (5A)

fuses ok...

(2) Please check that you have +12V at relay J493 (relay type 645 in the picture) pins 1 and 3 - when ignition ON.

I don't have 12v between 1 and 3 but if I put a jumper beetwen the 3 and 5 the blower is working

(3) Does the relay click when igntion is turned on - then +12V should be also on pin 5 (connecting to T17a pin 1).

I have tested the relay and it works

 

[SMS]

OK, my bad. This is crazy, but when I checked the fuses in fuse holder C, I removed every single fuse to check them, but I never thought one could be missing. So yeah, I feel dumb, but the SC28 fuse wasn’t there. I just put a 5A fuse in that slot, and everything is back to normal

My apologies, @mmi . I know you tried to find a solution for me—many thanks !

 

[mmi]

Excellent result

A lesson learned - always need to verify exact vehicle configuration. Just got distracted by looking for the fuse by light switch which indeed your van doesn't have. Instead there is the fuse SC1.
Thanks for sharing the challenge!

 

[SMS]

For the record, the van was in a garage for a window replacement. I think they may have removed a fuse to create a problem, hoping I’d have to go back to them for a fix (yes, this kind of scam exists). I can’t find any other explanation for the missing fuse. When I checked the online reviews of this garage, I saw that other users had complained about this type of conduct, though mainly related to window replacements.

Anyway, everything is fine now, and I’ve learned a few lessons as well.