A3 8V No Heat Diagnosis

[parker455]

Hi all,

I'm trying to diagnose why I've got no heating in an A3 2014 8V. 

All my temps seem to be fine and we're not overheating at all. 

I don't have VCDS so this makes it slightly more difficult however.. I have located the what I presume to be the in/out feed into the heater matrix.

The top hose feeding into this gets hot and I would assume this is the in, however the lower feed remains consistently cold even when up to temp. I am assuming the heater matrix is blocked, however is there a solenoid or valve behind this at all that could be stuck? 

My other way of trying to clear this blockage was to maybe disconnect the lines and pump fresh water through the matrix to try and clear any blockages from both ways. Thoughts?

The heating hasn't worked in around a year and i'm sitting at 110k miles so it's due a full coolant flush any minute anyway. 

Any help much appreciated! 

[Magnet]

Hello Tom,

I assume you have individual heater controls to separately regulate the temperature on driver and passenger sides, and by what you say about the different temperatures of the heater hoses, it is probable that both sides lack heat.

You could try squeezing the hoses with the engine up to temperature and running, and controls set to max. heat - obviously respecting all safety requirements. You might find you will feel air locks and the hoses will then reach the same temperature. I have my doubts this will work however, but worth a try. 

Blocked core? I seriously doubt this on a car of this age. Personally I would not try to back flush it? 

My stab at this is that it is some form of electrical control valve issue, but a guess it is.

By what you say about the fault existing since last year, it would seem that the car was marginally in/ just out of warranty, but....

Kind regards,

Gareth.

 

[parker455]

1 minute ago, Magnet said:

Hello Tom,

I assume you have individual heater controls to separately regulate the temperature on driver and passenger sides, and by what you say about the different temperatures of the heater hoses, it is probable that both sides lack heat.

You could try squeezing the hoses with the engine up to temperature and running, and controls set to max. heat - obviously respecting all safety requirements. You might find you will feel air locks and the hoses will then reach the same temperature. I have my doubts this will work however, but worth a try. 

Blocked core? I seriously doubt this on a car of this age. Personally I would not try to back flush it? 

My stab at this is that it is some form of electrical control valve issue, but a guess it is.

By what you say about the fault existing since last year, it would seem that the car was marginally in/ just out of warranty, but....

Kind regards,

Gareth.

 

Afternoon, Gareth.

 

Thanks for your response it's much appreciated.

So today I've had the car up to temp, heaters blowing on Hi (dual control but both set to hi) and have been squeezing all of the hozes I can get my hands on for the heating. Seems like this lower hose line is still dead cold so my thoughts are a heater valve behind this OR the core is blocked. There's been some talk online of the cores being blocked and I can't find any evidence of a coolant flush on this so it's possible.

I bought the car through work and it came from a VW authorised dealer around Feb 2015 at 6 months old so I would assume it may still have some warranty but I'm not too  sure I will have to check paperwork. 

I'm unfamiliar with the heating systems in these but have worked largely on 90's jap cars which are somewhat alot simpler. 

Is anyone aware of the solenoid that controls the heating? To me everything is pointing toward this core being blocked OR the valve control (if any?!). 

The thought of the backflush would be to see if anything is passing through the system, which currently it seems like it's not. Other option would be to leave the hot (in) feed and disconnect the line thats running cool and see if coolant passes through. I'm looking to do a full change on this anyway along with cambelt/waterpump so it could be a good time to address it. 

Any thoughts would be really helpful! 

Many thanks,

Tom

[Magnet]

Hello Tom,

Thanks for coming back with the extra information.

If the car was first registered? Feb. 2015 then the warranty would have expired in Feb. of this year - so too late now, so onward and upward! 

Blocked core? I would really simply forget that as a possibility, since the car is less than 5 years old. It is likely to still have its original OAT coolant which lasts at least for that time, and in reality nearer twice as long without major issue. As you point out, the coolant will be changed at the cambelt and water pump change ( suggest main dealer or Gates cambelt kit, and certainly main dealer only for the water pump - without question - in caps!) 

Back to heater:- I share your opinion that the problem here relates to a heater control valve, and if this were mine, I would wander into my local Audi dealer and ask about 'this valve'. They would then clarify what is what in relation to what it is, and if they tend to give problems.

Hopefully, someone much more up on this will come along on here and give you better advice.

Kind regards,

Gareth. 

 

 

[parker455]

On 9/12/2018 at 5:49 PM, Magnet said:

Hello Tom,

Thanks for coming back with the extra information.

If the car was first registered? Feb. 2015 then the warranty would have expired in Feb. of this year - so too late now, so onward and upward! 

Blocked core? I would really simply forget that as a possibility, since the car is less than 5 years old. It is likely to still have its original OAT coolant which lasts at least for that time, and in reality nearer twice as long without major issue. As you point out, the coolant will be changed at the cambelt and water pump change ( suggest main dealer or Gates cambelt kit, and certainly main dealer only for the water pump - without question - in caps!) 

Back to heater:- I share your opinion that the problem here relates to a heater control valve, and if this were mine, I would wander into my local Audi dealer and ask about 'this valve'. They would then clarify what is what in relation to what it is, and if they tend to give problems.

Hopefully, someone much more up on this will come along on here and give you better advice.

Kind regards,

Gareth. 

 

 

Hi there,

 

Sorry for my late response I've been working on this in the background.

So I had the dash apart and looks like the heater control flaps in the matrix are working, when AC is on the flaps function and without AC the flaps function from hot/cold.

This would indicate that the matrix itself is blocked OR the control flap itself has actually snapped i.e flap inside matrix isn't opening but I think this is unlikely..

Next step for me is a full coolant flush and I'm going to try and push fluid back through the matrix in the other direction.

I need to get a cambelt/waterpump changed in the next thousand miles or so, so I think I will be checking how pressured the system is via the waterpump as if this is damaged (shouldn't be, but never know) then it wont pressurise enough to push through the matrix. I'm thinking out loud here but might be totally wrong. 

It's getting cold so I need to get this sorted next weekend.

[Magnet]

I think your thinking regards possible water pump issues is a bit/way off the mark - as you suggest via. your second thoughts.

Heater matrix blocked on a 4 year old car??? -as I mentioned before, but OK sometime strange/very strange thinks happen! 

Chances of heater controls being at fault?  Still a reasonable possibility. 

Kind regards,

Gareth. 

 

[Dean7861]

Hi, sorry to jump on your thread but was this ever solved? im having the same issue on a 2013 (same model a3) 1.6 tdi, there is a lot of talk in regards to a silicon bag in the expansion tank that splits and blocks up the heater matrix.

[simon_m29]

Hi I’m having the same issue on 2013 A3 2.0L TDI, it’s been into Audi for a diagnostic. £400 later they’ve said they’re not sure! It could be 1 of 3 things:

1. Water pump/cam belt

2. Some exhaust manifold issue

3. Head gasket

Ive since heard it may be the Heater Control Valve. Does anyone know if this model car has one and whereabouts in the engine it is? 
 

Cheers in advance,

Simon

[Magnet]

Hello Simon from the north of God’s country,

Is the car loosing coolant? If not, there cannot be any connection (gasket failure) between coolant and combustion chambers - a la head gasket failure. 

Water pump? Well if around 60 years of playing around with motor cars counts for anything, then I’m still to come across a water pump which fails to circulate coolant without making its presence felt by making some sort of extreme protesting noises. 

Cam belt? diagnosis of this as the cause must simply equate to the dealer having a wish to upset your wallet! 

If this were mine Simon, I would be finding yourself a trusted local independent, before you spend even more money. 

Perhaps you could let us know how you get on.

Kind regards,

Gareth. 

[simon_m29]

Hi Gareth, 

thanks for the reply. Initially the heater stopped producing heat, then recently the coolant started dropping. After lots of searching I found that it may be the heater control valve. The apparent symptoms are no heat initially then loss of coolant through the valve. No idea if this is a valid issue or not 🤯
 

Simon 

[Magnet]

Hello Simon,

Thanks for giving the forum a bit more background. So, is the heater control valve leaking?

If it’s not, have you or the garage, found the source of the coolant leak? 

Kind regards,

Gareth. 

[simon_m29]

Audi didn’t say it was, leaking. They didn’t tell us they’d found the leak anywhere. No sign of any leaks anywhere. I’ve booked it in to the local garage in Conwy. I’ll have a look to see if I can find the heater control valve tomorrow see if there’s any sign of any leaking coolant 

[Magnet]

Good move I think Simon, but I would suggest you ask questions about their diagnosis and reasoning, rather than just listening to what they say. 

Personally, I would not be doing anything with the car until they look at it. 

Perhaps you could let us know how you get on. 

Kind regards, 

Gareth. 

[simon_m29]

I’ll definitely let you know the outcome 👍

[dan1991]

Hi all,

Having the same issue with my Audi A3 2.0 TDI 2014.

About 3 weeks ago my heaters stopped working, nightmare driving in the rain as the windows steamed upo so much! The only way to remedy this is to use the air con on the windscreen - yes its freezing and not the time of year to be sat in an air conditioned car first thing in the morning.
Anyway, i noticed my coolant has turned a very slightly darker (muddier) shade of pink but i didnt think it was that major but might have soimething to do with why my heaters have stopped blowing hot air. While getting my car serviced i asked the garage to take a look (very good guys, honest and fair) and see if they can find out what has gone wrong. 
Turns out my heater matrix is blocked solid, they attached a jet wash to the inlet to try and flush it and it was seized completely - most likely because i added inferior coolant over the past 2 years ive owned the car.
The garage advised me to put a coolant flush into the system to see if that will eat away at the blockage. I just went to halfords and bought a simple coolant flush from Holtz then gave it to the garage to use. They said i can drive it but to avoid long journeys for now, ill give it a few days of the flush working through the system and maybe, just maybe, it will clear and i can finally feel warmth again!

I will post results on the weekend but i fully expect to have the matrix replaced, they told me to do this the dash will have to be replaced and it will be a pig of a job but it needs to be done.

I didnt expect the heater matrix to seize up this quick, its only 5 years old but i would reccomend buying proper coolant and not use the cheapest available like i did. I know i am stupid in this respect, maybe others can learn from my mistake lol

Cheers
 

[Geoff-R]

On 10/23/2019 at 6:32 PM, dan1991 said:

Hi all,

Having the same issue with my Audi A3 2.0 TDI 2014.

About 3 weeks ago my heaters stopped working, nightmare driving in the rain as the windows steamed upo so much! The only way to remedy this is to use the air con on the windscreen - yes its freezing and not the time of year to be sat in an air conditioned car first thing in the morning.
Anyway, i noticed my coolant has turned a very slightly darker (muddier) shade of pink but i didnt think it was that major but might have soimething to do with why my heaters have stopped blowing hot air. While getting my car serviced i asked the garage to take a look (very good guys, honest and fair) and see if they can find out what has gone wrong. 
Turns out my heater matrix is blocked solid, they attached a jet wash to the inlet to try and flush it and it was seized completely - most likely because i added inferior coolant over the past 2 years ive owned the car.
The garage advised me to put a coolant flush into the system to see if that will eat away at the blockage. I just went to halfords and bought a simple coolant flush from Holtz then gave it to the garage to use. They said i can drive it but to avoid long journeys for now, ill give it a few days of the flush working through the system and maybe, just maybe, it will clear and i can finally feel warmth again!

I will post results on the weekend but i fully expect to have the matrix replaced, they told me to do this the dash will have to be replaced and it will be a pig of a job but it needs to be done.

I didnt expect the heater matrix to seize up this quick, its only 5 years old but i would reccomend buying proper coolant and not use the cheapest available like i did. I know i am stupid in this respect, maybe others can learn from my mistake lol

Cheers
 

How have you got on Dan?  Got exactly the same problem on mine and the garage recommended exactly the same remedy.  Has flushing it worked?

[simon_m29]

Further to my post above, my A3 has now been into 2 local garages. The first said they couldn’t find any reason for the faults. The second said it’s probably the heater control on the dashboard. I’ve sourced a new part and am trying to take out the old part and slide in the new one! Nightmare! Does anyone know how I remove it? There doesn’t appear any way of loosening the clips. 

[Geoff-R]

5 minutes ago, simon_m29 said:

Further to my post above, my A3 has now been into 2 local garages. The first said they couldn’t find any reason for the faults. The second said it’s probably the heater control on the dashboard. I’ve sourced a new part and am trying to take out the old part and slide in the new one! Nightmare! Does anyone know how I remove it? There doesn’t appear any way of loosening the clips. 

Are there any obvious clips on the new part? Sorry don't know how to fit it but if it doesn't screw in behind the dash I'd assume there is a release clip. I'm sure someone else will be along to advise. 

Let me know how you get on still no heaters either and the weather is getting colder!

[simon_m29]

Actual footage of me when I get out of my car

[simon_m29]

There’s clips on the 4 corners but the part is in so tight that I’m unable to see how to get at them to release them 

[Geoff-R]

Just a thought that part may be component protected so replacement isn't a simple case of swap out/in. 

[simon_m29]

Yeah it may need coding, the luck that I’m having at the moment it definitely will! 

[copkiller]

https://www.youtube.com/watch?v=775wCQk0R08

[cphaza]

Hi guys/girls.  Any one got an answer/follow up to this? Ive tested all my auxiliary electric water pumps which are working fine. Putting a hose through the heater matrix reveals 0 flow, Nothing at all, like its completely blocked solid. Is there some sort of flow valve in the dash or some other form of skulduggery that  i'm not in the know with? I'm doubtful of the control panel idea helping due to the lack of flow through the matrix. Cant see how the two could be related....  Unless there is a cunning flow valve somewhere yet to be discovered?  2014 1.6tdi with 45k on the clock by the way, full audi history.  HELP! its cold 🥶

[avtech999]

Hey, hopefully you have all solved this by now but having fixed mine in November - it was heater matrix being blocked by the sealant from the header. I replaced the heater matrix and all is well wit hthe world. yeah, A/C was becoming painful to clear the windscreen, lol. 

I tested the old matrix afterwards and it was completely blocked - both with normal flow and pressure flow.

It's a bit tedious as a lot of the interior has to come out, but it works a treat and is a damn lot cheaper than getting the garage to do it!