A6 owners please help.

[proff999]

Purchased used (2005) A6 3.0TDI from Lincoln Audi 7 weeks ago. Had issue with fuel gauge not working correctly and also the climate system had unusual feature where the central vents would blow hot air but after 5 minutes running would blow cold, even though the driver and passenger vents would continue to blow hot (24c).

The car went back to Audi 3 weeks ago and returned to me yesterday. They replaced the fuel gauge senders but with regard to the heater I got this

"Checked operation of heater vents, found temp difference from outer vents to the centre vent is a normal function of the basic air-con system on this vehicle"



Drove home yesterday via the fuel station, Filled up (£73) and parked on the drive. Turned on air con and it sounds like someone has put a piece of paper in the system as it makes an awful sound on anything over half fan speed and now after 5 minutes running with the heat setting set on 24c it blows cold out all vents.

The car is going back today as they failed to correctly seat the sender which resulted in having diesel streaming out all over the drive. As the car is going back in I hope they will look into the climate issues again.

If anyone with a similar basic air con system can advise me on whether the issue with differing tempretures between centre and outside vents is normal I would appreciate it. I have searched here for similar posts and found one which stated the following


Yes this is possible. There is a side vent flap contol motor that it if gets it wrong it lets hot air through the sides whilst the centre vent remains cold. If the motor and position pot have a connection problems or the temp sensor in the vent is getting the temp wrong and requesting hotter air. You need to have an arrangement with your Diagnostic garage to read the A/C ECU when you actually have the fault so you can drive in and they hook up without you turning it off or waiting. There may be an error code already stored.



I gave this information to Lincoln Audi but they inform me that I do not have a side vent flap control motor in my vehicle.


Any advice from other owners or techs would be greatly appreciated.


Scott

[Peter D]

Pre or post face lift. Though I think the A/C is the same and will look it up shortly. Regards Peter

[Peter D]

There is an option :
This control motor is only fitted on vehicles with operating and display unit, Climatronic control unit -J255- of “Convenience” type. This control motor is not fitted on vehicles with operating and display unit, Climatronic control unit -J255- of “Basic” type (opening in air distributor housing is sealed off and flap not fitted).
The 'Baisc' unit does not have independant control of the side vents and you can have different temps form the centre and side chest vents. Regards Peter

[proff999]

Thanks Peter for your swift and informed response. I have just found an earlier post of yours along with A8 Tech mentioning a similar sounding problem.

The difference in tempreture I would imagine is only a couple of degrees if working correctly. Mine is more like hot and cold with a difference in temps of around 10-15c.

"There is a heat exchange valve in the plenith chamber near the ns E box,the coolant flow is regulated by this duel valve for individual coolant circulation to passenger and drivers side and the solenoid sticks causing differing cabin temperature meaning a new valve is required.To add its very common for early 4f (new shape A6 2005 to 2007)and especially after 1 hours journey time"

[Peter D]

Do you mean between the centre vent and the outer vent or the difference between the two out vents. Regards Peter

[proff999]

Driver and passenger vents work perfect at 24c, two front central vents and rear vents blow cold mate.




To add insult to injury I have just got home to find an invoice for over £100 for the cleaning of the drive of a quarter of a tank of fuel that poured due to shoddy workmanship of the technician at Lincoln Audi following the fitting of new fuel sensors :(

[Peter D]

OK. We have established your system. There is a mode that requires to remove water form the air to control the humidity in the car. To do this the comprsssor cuts and and cools the air in the A/C unit but it should regulate the out going air temp measured by G191 in the central air vent. The air is cooled to remove water but then the heat is turned up to heat that air to the demanded temperature. You sholud not get long periods of cold air from the central vents. this air mixing is controlled by Flap Motors V102 and V197. PM me your email address and I send you the flow diagrams. You also have a TDI and if this only happens when not fully up to temp then it may be a problem with the Heater element for supplementary air heater -Z35- however I would expect that to adversly effect the side vents as well which it apparently does not as you get you 24 degrees. Regards Peter

[Peter D]

So send them the bill. Regards Peter

[proff999]

Peter,


I have been informed 5 times now by Lincoln Audi that my heating system is working correctly yet now the cold weather is beginning to land on us I still am sure somethings wrong.

If I set the temp to anything below 28 it blows cold air, If I set both sides to 24 it blows ice cold. As the car is Audi approved used am I correct in thinking I could get a second opinion from my own local dealership?


Thanks

Scott

[Michael Maurice]

Peter,

As the car is Audi approved used am I correct in thinking I could get a second opinion from my own local dealership?




Scott

Its certainly a route that I'd consider taking. But ask them what their policy is on such matters BEFORE booking the car in.

Michael

[Jack Ford]

Did you have any success in fixing this fauly prof999?

I have the same fault on my car now. Thanks Gavin

[NikB]

Apollogies if this is a very obvious and low tech answer and apologies also if I am mistaking this function for later modles but on my A6 I have the ability on the MMI to set the air that comes out of the center two vents to differ from that coming out of any other vent i.e. if this was set to be the maximum amount colder then I notice a distinct differnce in the temperature coming out of those two middle vents when compared to the rest.

Just a thought,

[singhl]

See http://www.fileden.com/files/2007/3/13/883667/2013883.pdf
for an explanation, the dealer should know about this it a recognised audi fault.