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Discussion Starter #1
Did anyone else have this problem, yet? My 2008 Touareg V8 with 108,000 mi has a problem with the heater/ac fan. It runs high speed always, even with the car off and key out. I am desperate here, I am pulling the fuse when I park and the stealer wants about $1500 to tear the dash apart and do some exploratory surgery on the poor thing.
 

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Check the coolant and oil temperatures with VCDS after you've parked the car, and then when it has cooled off, to see whether the temperature sensors are not reporting some wrong value. Of course also look for any fault codes.
 

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Check the coolant and oil temperatures with VCDS after you've parked the car, and then when it has cooled off, to see whether the temperature sensors are not reporting some wrong value. Of course also look for any fault codes.
Didn't he say blower fan? Did you read Rad Fan?
Not sure that overheating would trigger the interior fan to cycle..... that doesn't remove that much heat from the system!
 

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Discussion Starter #6
thanks, I will test the bitron, as the tech at the stealer is pretty much just guessing, so far. Wants to change out the heater/ac control panel for over $800 and the sensors under the dash for 3 hours labor plus there is always the "shop supplies" Always "shop supplies"
 

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Same thing here. Went out to start T-reg and battery was dead. Once I jumped it off, the fan will not stop blowing even with fan control set to off...until the battery dies again. Is there a quick fix? Blower fan fuse is where I'm gonna start.
 

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Discussion Starter #8
If you find out what is causing this, let me know asap. This really sucks, I am pulling fuse whenever i stop the car, for now. Can hardly justify spending that much on a repair to the heater and it seems they are only guessing at the repair right now
 

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So, I tried your trick, pulling out the 40A fuse on the driver's side at the top of the fuse panel, cuts power to the AC/blower fan. I charged up the battery and got the VW running.

I then plugged in my Ross-tech VCDS and cleared out all the fault codes because my battery had run dead and set off a ton of irrelevant low voltage fault codes. I restarted the VW and then checked for fault codes again and found the following:

Address 08: Auto HVAC Labels: 7L6-907-040.clb
Control Module Part Number: 7L6 907 040 AD
Component and/or Version: CLIMAtronic R/L 4326
Software Coding: 0020030
Work Shop Code: WSC 31414 790 00001
VCID: 72EA5DDD696F4ADAD3-8026
1 Fault Found:

00353 - Function Return Message from Fresh Air Blower Regulator
001 - Upper Limit Exceeded
Freeze Frame:
Voltage: 13.50 V
Voltage: 6.05 V
Voltage: 11.77 V
Voltage: 14.00 V


I found SSP301 The Touareg heating/air-conditioning system
http://www.volkspage.net/technik/ssp/ssp/SSP_301.PDF

I have the 2C-Climatronic system.

My thought was that the Sender for blower control, front G462 (Bitron) may be going bad but, page 73 in SSP301 states:

Function:
"The sender for blower control is activated by the Climatronic control unit using a pulse width modulated signal (PWM). Power is supplied to the control by the Climatronic control unit J255. According to its demands, the sender regulates the blower motor in the air-conditioning unit."

Effect of drop-out:
"If a blower is defective, the entire heating and cooling function of the air-conditioning system fails. The diagnostics can be used only indirectly to localize a fault on the blower control unit or on the blower. For this purpose, there is a resistor in the blower control unit; this is connected with the minus pole of the blower motor. Due to this arrangement, the control unit receives ”acknowledgement information”, which can be used to determine whether the fault is at the sender, at the blower or both. There is no direct indication for a fault on the control or on the blower. However, the voltage signal of the resistor in the blower control is not a signal for the actual voltage on the blower motor, but rather a signal with which the Climatronic control unit can ”observe” the behavior of the sender for the blower control."


So, that being said, I don't know if the fan running all the time necessarily means that the G462 is bad, but power is still somehow getting to the blower fan even when the ignition is off. I know there is a feature on the car which allows the fan to run when the car is off, it is the Residual Heat Function (REST) but it usually operates at a reduced blower fan speed to prevent the battery from running down too much so I don't think that is the problem.

Back in the summer my fan quit working for a few weeks and it has been making sounds for the past year or so. I also noticed, during this latest vehicle startup, a slight hot electrical wire smell after the VW had been running a few minutes. I think my fan motor is at the end of its life and I am going to start by replacing it Part#7L0-820-021-Q (right hand drive). If that doesn't do it I'll replace the G462 (Bitron) Part#7L0-907-521-B
 

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You are overthinking the problem. Look inside the bitron.

I have a problem. The blower runs all the time and you can not change the speed at a constant speed. It can not be turned off even after removing the key from the ignition. I noticed that if I turn it to OFF, the engine will slightly throttle as short as it would (but the fuses did not blow).

VCDS error

00353 - Function Return Message from Fresh Air Blower Controller
001 - Upper Limit Exceeded
Freeze Frame:
Voltage: 14.10 V
Voltage: 5.89 V
Voltage: 10.48 Volt
Voltage: 14.00 V

I dug a bit and it turned out that the contacts on the resistor pole were damaged. Probably from old age and temperature. They burned up and melted the socket in the resistor housing and plug. The old Bitron is trash.
Still, replacing the fan motor is a good idea. You can replace the fan motor now or replace it later, but you will eventually replace it. The fan motor is a wear item in this vehicle.
 

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Discussion Starter #11
Yes, looking at the schematic, looks exactly like bitron, G462 is sending the ground to the heater motor, so might have gone bad, and that explains why motor runs with key off and removed. This is the only place the motor would receive power, the positive side is connected always and the ground is switched on or off from a signal the bitron is receiving from the control unit, or in this case even not getting a signal, it is still grounded because???the bitron is shorted out??
 

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It looks like the large spade lugs (which modulate the power to the fan) inside the bitron shorted. It will be interesting to see if the same thing happened to both of you. If you replace the bitron and fix the problem, please check the old bitron and let us know.



.
 

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Jip. Just had the same.

New bitron on the way. I also requested a piece of the harnass from the breaker.
 

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There is a cutaway at the back of the cubby hole. Very easy access to it.

Just prod around with your nail, you will find the perforation lines.
 

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After taking some clearer photos of the connector, I found the part number 1J0972752. I think I have lots of options now. I'm going to strip the insulation back and see how far that corrosion goes.
 

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