rear footwell heaters

[H-M3]

as its getting cold passengers start to complain about rear being cold. Has anyone actually repaired the heater elements or is it just replace with secondhand ones? Would prefer fix as no guarantee the SH units will last. Any thoughts??
ta

[mannyo]

its replace only.

you still get heat out of the footwell vents even though the electric elements are not working, after all the D3 only has them if you have the rear climate controls. All the other models make do with the usual arrangement. The heaters only add a small amount of heat, and as others have posted in the past finding a D3 with them still working is very rare. Neither of mine work, and I've not had comments from rear seat passengers when I have them. If the lower vents are cold then its possibly a stuck flap motor rather than the heaters causing issues.

[Lee S]

Do they show up on a scan as being inoperative or do they just go?

[H-M3]

Thanks guys. My one does have the rear climate inc heated seats. I think you might be right mannyo poss the flap might be stuck. Lee I don't have VCDS so will have to pop down to my Guru Marcin

[mannyo]

If they are faulty they show up on VCDS, but the flap motors will also show.

This is what a scan of mine shows (old scan)

3 Faults Found:
00066 - Right Rear Footwell Heater (Z43)
012 - Electrical Fault in Circuit
Freeze Frame:
Fault Status: 01101100
Fault Priority: 3
Fault Frequency: 1
Reset counter: 62
Mileage: 210468 km
Time Indication: 0
Date: 2014.03.13
Time: 18:22:12

Freeze Frame:
Voltage: 11.50 V

01087 - Basic Setting Not Performed
005 - No or Incorrect Basic Setting / Adaptation
Freeze Frame:
Fault Status: 01100101
Fault Priority: 2
Fault Frequency: 1
Reset counter: 42
Mileage: 208636 km
Time Indication: 0
Date: 2014.02.01
Time: 10:41:38

00065 - Left Rear Footwell Heater (Z42)
004 - No Signal/Communication
Freeze Frame:
Fault Status: 01100100
Fault Priority: 3
Fault Frequency: 1
Reset counter: 62
Mileage: 210468 km
Time Indication: 0
Date: 2014.03.13
Time: 18:22:13

Freeze Frame:
Voltage: 11.50 V

[M-A8]

I've got two sets of these
One on the car and one in the garage.

First screenshot is a set which is on the car at the minute.
Second screenshot is of the replacement pair I have on the shelf, but only right heater has an error so the left one could ok ?? Ignore the blower fault, that's not my car's.
Why both don't have the same error?? One is 012 while the other is 004.

[H-M3]

Originally Posted by mannyo

its replace only.

you still get heat out of the footwell vents even though the electric elements are not working, after all the D3 only has them if you have the rear climate controls. All the other models make do with the usual arrangement. The heaters only add a small amount of heat, and as others have posted in the past finding a D3 with them still working is very rare. Neither of mine work, and I've not had comments from rear seat passengers when I have them. If the lower vents are cold then its possibly a stuck flap motor rather than the heaters causing issues.

How do you rectify the stuck flap then??

[47p2]

The rear heater elements that are prone to breaking are there to heat the rear compartment when the front is set colder than the rear. Therefore if the front is set at 22 the rear should heat to 22 or above. However if the front is set to 18 and the rear passenger wishes 22 but the heater element is broken then the rear will only heat to 18

[snapdragon]

I thought I would have a look at my heaters as they are both dead. They are easy to remove - it takes 60 seconds.

I was hoping to replace the element as you can buy various 12v heating elements from china.

1. slide the front seat all the way forward.
2. Pop off the two round plastic nut covers.
3. Remove the two 10mm nuts.
4. Lift the flap of carpet at the front and back and you will see how it needs lifting at the back over the studs and it is inserted into a duct at the front.
5. Undo the electrical connector at the side/front. Typical VAG type type. Push it in hard, press the tab hard with your thumb until it clicks in and then pull the plug out. If it doesn't come out, repeat but lever it out to unplug it while still squeezing the tab.
6. Lift at the rear and withdraw.

Well, inside the house, I split the two casing halves which are held together along it's seam by 6 metal spring clips.

What a terrible design. It works by overheating several transistors with heatsinks attached! There is what is possibly a blue bead thermistor to give temperature feedback, and maybe a thermal fuse. It is all potted in black epoxy which make it's hard to reverse engineer, if not impossible.
What a joke. It is worth about £5 each but Audi charge £200 each and they don't last at all.

I am thinking of breaking it all out and seeing if I can remake the original design with new components.

While I was taking them out, I sadly found both to be wet and the foam insulation under both seats sopping wet. I have the pleasure of looking into that now. I have no sunroof, so hoping it's the A/C drains.

Attachment 22355

Attachment 22356

Attachment 22357

Attachment 22358

Attachment 22359

Looking at the wiring diagram, we have:
PINOUTS
1 Switched 12V
2 LINBUS signal
3 LINBUS ground
4 Ground

As it has LINBUS connections, there is no way to turn on/off/regulate without retaining the circuit that is hidden in a trough of epoxy.



Attachment 22360

[steamship]

Originally Posted by snapdragon

It works by overheating several transistors with heatsinks attached!

I'm not versed in electronics but that was exactly my thought when I dismantled mine to see if they could be repaired. Ended up just binning them.