Wingmirrors - Not demisting?

[mpc]

I have noticed in this colder weather that my wing mirrors do not seem to be demisting. Is there a dedicated fuse or something for the wing mirrors that could have blown? Could it be something else obvious?

I have posted in another thread that the rear window takes a very long time to demist - could they all be related?

My car is an A4 Avant B8 S Line 2.0 TDi

 

[jetty]

Has to be below a certain temperature for them to work - they are really a "de-icer" rather than "de-mister".

 

[xpoweruk]

Do you have the mirror adjuster in the neutral/middle position?
iirc it only heats the mirrors in said position

 

[rum4mo]

That is annoying if true, most of the time that I've needed to clear the mirrors on my old B5 Passat, it was due to driving, in cold weather, through an area of warmer moist air, so the mirrors misted up quickly as they were cold enough for the water vapour to condense on to. Also, I'm sure that I've had the same use for these heaters with my S4 mainly when driving away from a freezing cold garage when the ambient temperature has risen nearby so the windows and mirrors mist up.

 

[rum4mo]

Do you have the mirror adjuster in the neutral/middle position?
iirc it only heats the mirrors in said position

That bit is certainly true, and that is what caught me out with my old B5 Passat, I thought that it would have been the same as my old VX Cav GSI 4X4, in as much as if left in the "on" position, the mirrors would (also) get heated when the rear window heater was on! That cost me two new heated mirrors on the Passat!!

 

[razza1]

I've used mine to clear rain drops off them when temp is warm, so not sure that holds true?

 

[sixpot]

I have noticed in this colder weather that my wing mirrors do not seem to be demisting. Is there a dedicated fuse or something for the wing mirrors that could have blown? Could it be something else obvious?

I have posted in another thread that the rear window takes a very long time to demist - could they all be related?

My car is an A4 Avant B8 S Line 2.0 TDi

If the mirrors still move around electrically, then I'd be certain the heating elements have burned out. It's far too easy to leave them permanently switched on, with having a switch that isn't so obvious when it's on. This will shorten the life of the heating elements, hence it's quite common for them to stop working.The heating function will stay on all the time regardless of outside/ambient temp, as long as they are left switched on.

 

[jetty]

Mine only work when there is ice build up - don't work on a day like today where they are covered in dew. Not quite sure what's going on there! (mine is a 2009 sline if that makes any difference)

 

[benjie]

I've used mine to clear rain drops off them when temp is warm, so not sure that holds true?

Same here.

 

[Slackworth]

If the mirror heaters have burnt out, a scan of VCDS will show this up.

My passenger mirror is currently in the same boat but given how much they are and the fact I'm now in the process of having to replace my drivers side due to some **** on the road crossing the white line, it'll have to wait!

 

[rum4mo]

If the mirror heaters have burnt out, a scan of VCDS will show this up.
-------------------

In my VW experience that might not be so, when these heaters burn out they do not cleanly, so leave a carbonised track on the backing film, that means if you checked the resistance of a burned out heater you will still see maybe 1.5K ohms instead of a few ohms - that fooled my car's controller, it was only when I unplugged the heaters that a fault was logged.

 

[Slackworth]

Interesting - I've checked the terminals themselves and they're fine but currently have this error on mine:

Address 52: Door Elect, Pass. (J387) Labels: 8K0-959-792.clb
Part No SW: 8K0 959 792 B HW: 8K0 959 792
Component: TSG BF H10 0170
Revision: Serial number: 0000006886948
Coding: 011C02205E01410001
Shop #: WSC 06325 000 00000
VCID: 3E74A49EA9DF20CE43-806A

1 Fault Found:
00920 - Heated Outside Mirrors; Driver Side (Z4) / Passenger Side (Z5)
012 - Electrical Fault in Circuit
Freeze Frame:
Fault Status: 01101100
Fault Priority: 3
Fault Frequency: 70
Reset counter: 253
Mileage: 124026 km
Time Indication: 0
Date: 2016.01.04
Time: 19:39:24

 

[aprilia dude]

I think u can turn on the mirror demist by havin the selector switch in the "said" position the push the knob towards the heated symbol ..and they shud come on for 15 mins

 

[rum4mo]

When you say you have checked the terminals, do you mean that you removed the supply leads to the mirror and checked the mirrors resistance, or just the voltage?
That logged fault looks like the heaters are u/s, which was more than I found in my 2000 VW Passat, maybe progress on the diagnostics system?

 

[rum4mo]

I think u can turn on the mirror demist by havin the selector switch in the "said" position the push the knob towards the heated symbol ..and they shud come on for 15 mins

I'd hope that the 15 min operating time would be correct as that would save the heaters, but I can't say!

 

[razza1]

If the mirrors still move around electrically, then I'd be certain the heating elements have burned out. It's far too easy to leave them permanently switched on, with having a switch that isn't so obvious when it's on. This will shorten the life of the heating elements, hence it's quite common for them to stop working.The heating function will stay on all the time regardless of outside/ambient temp, as long as they are left switched on.

They only come on when they are in the middle position and the rear heated screen button is pressed, they can't be left on unless you keep pressing the rear heater button when it goes off...

 

[Slackworth]

When you say you have checked the terminals, do you mean that you removed the supply leads to the mirror and checked the mirrors resistance, or just the voltage?
That logged fault looks like the heaters are u/s, which was more than I found in my 2000 VW Passat, maybe progress on the diagnostics system?

U/S?

I've checked the voltage on the terminals themselves but haven't checked the resistance on the mirror - may be worth a go to be fair.

I can run the test on VCDS for the heated mirrors - oddly they run at 100% load for a few secs before it drops to 0.0% and causes the error code (if you clear it beforehand).

 

[rum4mo]

They only come on when they are in the middle position and the rear heated screen button is pressed, they can't be left on unless you keep pressing the rear heater button when it goes off...

Well that might be build date specific, the heaters on my early 2011 S4 certainly come on if demanded without the heater window heater on, as did/do the mirror heaters on my old 2000 Passat, wifes old 2002 Polo and my wife's current 2015 Polo.

 

[jdp1962]

U/S?

Abbreviation for "useless".

 

[rum4mo]

Abbreviation for "useless".

Oh, maybe outside the scientific/engineering world, but within it normally means UnServicable, though both point to a similar condition! (which there is another well used word for)

 

[jdp1962]

Oh, maybe outside the scientific/engineering world, but within it normally means UnServicable, though both point to a similar condition! (which there is another well used word for)

Thanks, @rum4mo, as you might gather, I have an unscientific mind.

 

[rum4mo]

Thanks, @rum4mo, as you might gather, I have an unscientific mind.

Maybe you need to watch more rubbish USA films as that was probably where the scientific/engineering world took the lead from???

Edit:- had to change something that did not pass the badness filter!

 

[Zafi]

The heaters are on all the time, not temperature dependant or anything to do with the rear demister.
I never use my rear demister, always have my mirrors heated. Driving in the rain without heated mirrors is dangerous as rear vision is impaired.

 

[rabhrab]

They only come on when they are in the middle position and the rear heated screen button is pressed, they can't be left on unless you keep pressing the rear heater button when it goes off...

Mine are the same as razza1, above. Mine is a 2009 S4, same year as razza1, so looks like it differs depending on age?

 

[razza1]

The heaters are on all the time, not temperature dependant or anything to do with the rear demister.
I never use my rear demister, always have my mirrors heated. Driving in the rain without heated mirrors is dangerous as rear vision is impaired.

Going to have to try this, as according to the manual, page 68, the rear view mirrors are heated when the switch is in the middle position, dependant on temperature, and stay on until the ignition is turned off, even if the knob is turned off the middle position...

 

[rum4mo]

This heater controller strategy seems to still be fluid in the VAG world as it has been so for the 16 years that I have been an owner of their products. The old Passat view of this seemed to go along the lines of "yes, but Audi heaters are protected by thermostats" - but if current Audis have thermostatic protection on their mirror heaters, then why is there an ON/OFF switch?

Edit:- I can't claim to have remembered what I've read about this in the handbook, though as the Skoda gang say, "a lot is lost in translation into English" - though maybe in their case it is German > Czech > English ?

 

[KudoWarrior]

I currently have the same issue with mine.
Still not sure what the issue could be, taking it over to a mates this week to scan it with VCDS. I'll let you know if any error code pops up which could help with your own issue.

 

[sixpot]

They only come on when they are in the middle position and the rear heated screen button is pressed, they can't be left on unless you keep pressing the rear heater button when it goes off...

That's not how they work in my 2009 car. They are independent of the heated rear screen.

 

[razza1]

That's not how they work in my 2009 car. They are independent of the heated rear screen.

See my post following that one, sounds like I might be wrong..

 

[jdp1962]

Anyone getting the impression that Audi changes the methodology every model year just to confuse us?

 

[razza1]

Ok, tried it this morning and they came on when in middle position and no rear heater on