Glad to hear you have heat again. With that core you bought, did you have to buy anything extra like the foam or o-rings? Or did it come with everything you needed for the job. 

13 hours ago, Christie365 said:

Glad to hear you have heat again. With that core you bought, did you have to buy anything extra like the foam or o-rings? Or did it come with everything you needed for the job. 

The one I bought only came with the foam to wrap round the core. I did buy the additional fitting kit which had new clamps and O rings, but taking the old one off and inspecting the old kit, it was in good working order, so I didn’t need the new kit. 
The fitting kits can be bought on eBay, part number 4M0898037B

Hi Guys, 

I am having the same heating issue on my 2018 A4 Allroad.

Can you help me with the exact location of the heater core at my car? 

There are some conflicting info on the web, some saying that complete dash must be removed.

My car is lefthand drive.

Many thanks,

Ivan

 

 

14 hours ago, Ivan Drago said:

Hi Guys, 

I am having the same heating issue on my 2018 A4 Allroad.

Can you help me with the exact location of the heater core at my car? 

There are some conflicting info on the web, some saying that complete dash must be removed.

My car is lefthand drive.

Many thanks,

Ivan

 

 

Hi,

 

It`s behind the glove box towards the central console. If you remove the glove box you can see the pipes and the core, however, to remove it as someone said previously in this thread you will need to remove part of your heaterbox fan. Someone said it took around 2 hours to get it changed with lots of screws. I plan to change mine soon, maybe in a couple of weeks and I plan to take a few pictures of the steps and post them here.

3 hours ago, Vytas said:

Hi,

 

It`s behind the glove box towards the central console. If you remove the glove box you can see the pipes and the core, however, to remove it as someone said previously in this thread you will need to remove part of your heaterbox fan. Someone said it took around 2 hours to get it changed with lots of screws. I plan to change mine soon, maybe in a couple of weeks and I plan to take a few pictures of the steps and post them here.

Thanks, what is not clear to me(please see the photo) is this a UK glovebox removal. If so than on lefthand drive side I would need to approach it from the steering wheel side, right?

Another thing that don’t make sense is if the heater core is blocked then there won’t be any(or poor) heating in the front either. My heating at the front is great, on the back console and back footwell only cold air is coming out when in heating mode.

Could it be that some flap/servo motor that redirects cold/hot is stuck in cooling mode?

Btw, air conditioning works great, no problem there.

All the best!

 

20 hours ago, Ivan Drago said:

Hi Guys, 

I am having the same heating issue on my 2018 A4 Allroad.

Can you help me with the exact location of the heater core at my car? 

There are some conflicting info on the web, some saying that complete dash must be removed.

My car is lefthand drive.

Many thanks,

Ivan

 

 

Hi,

From what I found when researching, if it’s just the core you need access/removal to, then it’s just the glove box (for rhd) or the steering column assembly/cover (for lhd). 
If you need access/removal, then it’s the whole dash out. 

My A4 had poor heat at front and no heat at the rear. With the new core I now have good heat from both.

Yours does sound like it could be a flap/paddle issue. 
Do you have a Carista dongle by any chance? I do, and there’s a calibration check that can be done with Carista that will check and reset the flap/paddle positions. 

1 minute ago, ian.f said:

Hi,

From what I found when researching, if it’s just the core you need access/removal to, then it’s just the glove box (for rhd) or the steering column assembly/cover (for lhd). 
If you need access/removal, then it’s the whole dash out. 

My A4 had poor heat at front and no heat at the rear. With the new core I now have good heat from both.

Yours does sound like it could be a flap/paddle issue. 
Do you have a Carista dongle by any chance? I do, and there’s a calibration check that can be done with Carista that will check and reset the flap/paddle positions. 

Hi Ian,

Thank for your suggestions. Yes I have Carista and I did a HVAC calibration, nothing changed.

On Thursday I will visit coding specialist who is certain that he can fix the issue.

I will keep you updated. 

 

15 minutes ago, Ivan Drago said:

Hi Ian,

Thank for your suggestions. Yes I have Carista and I did a HVAC calibration, nothing changed.

On Thursday I will visit coding specialist who is certain that he can fix the issue.

I will keep you updated. 

 

Hi Ivan,

 

In your case, i would remove the steering column cover and measure the temp at the bottom of the heater core, as rear vents get the air from the bottom of the heater, at least if it is hot, then you will know for sure it`s not your heater core/matrix. As well have a look in your coolant expansion tank for any silica at the bottom, as that's what starts blocking the heater when it bursts.

14 minutes ago, Vytas said:

Hi Ivan,

 

In your case, i would remove the steering column cover and measure the temp at the bottom of the heater core, as rear vents get the air from the bottom of the heater, at least if it is hot, then you will know for sure it`s not your heater core/matrix. As well have a look in your coolant expansion tank for any silica at the bottom, as that's what starts blocking the heater when it bursts.

Thanks, I will look into that tomorrow. 

One more maybe important point, when set to “Sync” and “Auto” there is no blowing at the back and middle central front console at all. When I switch to manual and crank up the temperature it do blows hot from all the vents in the front, rear starts blowing but at outside temperature(or close to outside temp).

So i have done the Heater core matrix change and it was not difficult without any mechanical knowledge, however would recommend to have someone to help you as at some stages it looks like you need another pair of hands just for holding a pipe in position or a torch.

Started by removing the glove box and some covers on the passenger side:

 

Then you will be able to see the heater core and pipes.

 

After this, remove the media unit and disconnect all cables, all colour coded and different types of connectors, so it will be easy to connect back, but just in case, take a picture for reference.

 

 

 

Remove the foam cover

 

And remove the fan, few screws holding it.

Remove the sensor in front of the heater matrix, which is blocking the bottom part of it.

Place a tub under and start loosening the pipes.

After that, push the pipe out of the way and slide the heater core out.

 

Change the core and do everything back in reverse. I have bought new seals and clamps as well for the pipe, don`t need to, but it was just in case. Would at least recommend changing the seals. Was very difficult to alight the pipe and at the same time tighten the screws when putting back together as there was not a lot of room and make sure you put clamps facing the same way as they were due to not blocking the plastic going back in at the bottom of the heater core.

Prior to the task, I completely flushed the coolant and changed the coolant tank, which I bought for 30£ as there was a lot of residue sitting at the bottom of it.

Job done in April.

Any questions I will try to answer when I can.

Thanks and good luck,

 

Thanks for the detailed report Vytautas.

Great guide. Well done on the job. 
 

If I may add; when I did mine I needed to remove the fan motor as there wasn’t the room to get the core out otherwise. 
 

Just in case anyone has the same experience as me. 

Hi Ian,

It`s in the 5th picture from the bottom in my guide as well.

Regards 

Vytas

On 6/30/2025 at 3:04 PM, Vytas said:

So i have done the Heater core matrix change and it was not difficult without any mechanical knowledge, however would recommend to have someone to help you as at some stages it looks like you need another pair of hands just for holding a pipe in position or a torch.

Started by removing the glove box and some covers on the passenger side:

 

Then you will be able to see the heater core and pipes.

 

After this, remove the media unit and disconnect all cables, all colour coded and different types of connectors, so it will be easy to connect back, but just in case, take a picture for reference.

 

 

 

Remove the foam cover

 

And remove the fan, few screws holding it.

Remove the sensor in front of the heater matrix, which is blocking the bottom part of it.

Place a tub under and start loosening the pipes.

After that, push the pipe out of the way and slide the heater core out.

 

Change the core and do everything back in reverse. I have bought new seals and clamps as well for the pipe, don`t need to, but it was just in case. Would at least recommend changing the seals. Was very difficult to alight the pipe and at the same time tighten the screws when putting back together as there was not a lot of room and make sure you put clamps facing the same way as they were due to not blocking the plastic going back in at the bottom of the heater core.

Prior to the task, I completely flushed the coolant and changed the coolant tank, which I bought for 30£ as there was a lot of residue sitting at the bottom of it.

Job done in April.

Any questions I will try to answer when I can.

Thanks and good luck,

 

Hi Vytas, 

Thanks for providing such a detailed step-by-step. I’m planning on tackling mine soon. I was wondering if you could explain the process you went through for the coolant flush you did prior to swapping the matrix, I’ve seen people do different things. Are you heaters still working good? 
 

Thanks 

On 7/1/2025 at 7:58 PM, ian.f said:

Great guide. Well done on the job. 
 

If I may add; when I did mine I needed to remove the fan motor as there wasn’t the room to get the core out otherwise. 
 

Just in case anyone has the same experience as me. 

 

On 12/14/2025 at 9:24 PM, Christie365 said:

Hi Vytas, 

Thanks for providing such a detailed step-by-step. I’m planning on tackling mine soon. I was wondering if you could explain the process you went through for the coolant flush you did prior to swapping the matrix, I’ve seen people do different things. Are you heaters still working good? 
 

Thanks 

Hi Christie,

Yes, the heater still works perfectly.

For the flush emptied the coolant from the radiator at the bottom screw, then changed the coolant tank as i could see it had sediments of silica in it. After this worked on the core matrix. Just make sure you have something to catch more coolant when u undo the pipe going to the heater core, as there will be more coolant from the pipes and make sure you properly put the pipe clamps on to the new matrix, as it is a bit awkward when you're upside down with not much room to play. Then just refill the new coolant, and it self-bleeds.

I’m back. I had mine flushed last year and it worked for a while but now I’m back to barely any heat so have ordered the core and fitting kit and going to try tackle it myself thanks to everyone’s guides so far. One question I do have is how did people refill the coolant? Did you do it the old school/self bleed way or use vcds or vacuum fill? 
 

My plan was to drain coolant from bleed screw, replace the core, then fill with coolant and self bleed topping up as required. 
 

Any/all advice appreciated. 
 

Thanks

12 hours ago, Christie365 said:

I’m back. I had mine flushed last year and it worked for a while but now I’m back to barely any heat so have ordered the core and fitting kit and going to try tackle it myself thanks to everyone’s guides so far. One question I do have is how did people refill the coolant? Did you do it the old school/self bleed way or use vcds or vacuum fill? 
 

My plan was to drain coolant from bleed screw, replace the core, then fill with coolant and self bleed topping up as required. 
 

Any/all advice appreciated. 
 

Thanks

That sounds good to me. This is what I have done.

How did you remove the drain plug? Just using a flathead screwdriver? I’m worried in case I break mine. In the middle of doing mine now 

On 1/19/2025 at 9:16 PM, ian.f said:

Hmmm good shout. So a bit of grease round the mouth on the core, then the o ring should slip in easier?

I can’t see any specific connection/connector/locator, but will check tomorrow. 

if I take the o ring out, the pipe sits in flush to the core and I can fit the connector…but it leaks badly…obviously!

Having the same problem getting the core attached to the pipes. How did you manage in the end? Thanks

 

17 hours ago, Christie365 said:

How did you remove the drain plug? Just using a flathead screwdriver? I’m worried in case I break mine. In the middle of doing mine now 

Can`t remember if it was a wrench or a flat head screwdriver, but definitely one of them.

On 1/25/2026 at 4:23 PM, Christie365 said:

Having the same problem getting the core attached to the pipes. How did you manage in the end? Thanks

 

I used a little grease on the outside of the pipes to get them to locate. Before they wouldn’t connect. After a little grease they slid together perfectly. 

Thanks all, replaced it the other day and now have heat back finally. If anyone else is doing theirs I’d maybe suggest disconnecting the battery as well to avoid getting a safety system fault with unplugging the airbag, hopefully get lend of an OBD11 to clear it. 

Glad to hear it. Please tell us if you found silica gel crystals, and how you bled air after refilling.

17 hours ago, cliffcoggin said:

Glad to hear it. Please tell us if you found silica gel crystals, and how you bled air after refilling.

I still have my old radiator in the garage and am gonna cut it open at some point and post some pictures.

Thanks. I hope Fraser will do the same.