No heat from vents

[jjp]

You might have an air lock or another reason as it sounds like warm/hot coolant is not getting into the matrix. One way to check is test the temp of the 2 pipes in/out of the matrix and see. The IN pipe should be hot and the OUT pipe not as much (assuming you have the heating on).

Theoretically you can access the pipes in the engine bay by the bulkhead but it's easier if you do it from the passenger footwell directly onto the matric pipes. You'll need to remove the trim than runs by the central tunnel but it's only a couple of T20's or something.

View attachment 20004

I bought one of these to check mine.

Etekcity Lasergrip 800 Non-contact Digital Laser IR Infrared Thermometer, Temperature Gun, -50°C~750°C ( -58°F~1382°F ), Yellow/Black (Not suitable for measuring body temperature): Amazon.co.uk: DIY & Tools

Shop Etekcity Lasergrip 800 Non-contact Digital Laser IR Infrared Thermometer, Temperature Gun, -50°C~750°C ( -58°F~1382°F ), Yellow/Black (Not suitable for measuring body temperature). Free delivery on eligible orders of £20 or more.

www.amazon.co.uk

The coolant system is in 3 parts and quite complex. The only way to fully bleed is it apparently by VAG using posh kit to open/close valves etc - unless your garage did that. Some pipes are very narrow, are subject to blockages and could have debris in them (the crud that blocked your matrix will find any restriction in the system to park up - my thermostat housing was full of it). The system is meant to be self bleeding though and can take a while to settle. I'd keep topping it up (if feasible) and see how you go.

Could still have bits and bobs of silica in places.

mine is the same, hot passengers and mildly warm / sometimes cold drivers side.

going back in tomorrow for another coolant flush FOC

Let me know if the coolant flush helps BigJase88 ?

Brian Cheers pal, im hoping it is just an air lock, well crossing my fingers on it, the garage that replaced my matrix did flush out the system, but my blockage wasn't due to the silica bag, it was down to limescale/ what I thought looked like rust when he showed me the old matrix, he could only reckon that the previous owner hadn't used coolant but most likely water instead!! So I dread to think what else is buggered. I'm pretty sure he removed the silica bag for me aswell as he does that for his vag customers.

 

[BillyCool]

Brian Cheers pal, im hoping it is just an air lock, well crossing my fingers on it, the garage that replaced my matrix did flush out the system, but my blockage wasn't due to the silica bag, it was down to limescale/ what I thought looked like rust when he showed me the old matrix, he could only reckon that the previous owner hadn't used coolant but most likely water instead!! So I dread to think what else is buggered. I'm pretty sure he removed the silica bag for me aswell as he does that for his vag customers.

Just so you know, the `rust` is probably a combination of gunk and casting sand from the engine block. Another known issue that blocks the matrix. When I unsuccessfully flushed mine out, loads came out. Othe people have posted photos of much the same (this is not my photo)

As the matrix cooling system is so small (I got about 500ml out of mine when I changed matrix), the majority of coolant is in the radiator circuit. As I have my cambelt/pump/thermostat (+housing) changed, I got my mechanic to ditch as much coolant as he could.

I've never had a `proper` flush but at the moment all is good and the car heating is nice and toastie.

Worse case, I'll fit another matrix in a few years. Still cheaper at €80 and 2 hours of my time.

Let us know how you get on.

 

[SteveFR]

Well my Leon is back from garage with a new heater matrix fitted, a relief to have lovely warm air demist my spectacles whilst driving in the freezing fog!

Whilst stripping out dashboard the mechanic discovered a leak which had made the passenger footwell carpet damp plus got into the airbag module, so will have to pop back in a fortnight to have that reactivated once everything has dried out.

 

[SteveFR]

Unfortunately the airbag module is knackered and SEAT cannot get a replacement to my local indie garage before Christmas but on the upside I can stick that on January’s credit card bill instead.

Oh and FWIW this video from EngineeringExplained featuring HumbleMechanic popped up on my YouTube suggestions and might be of interest to some...

 

[UnHandyAndy]

I am experiencing a similar issue with the Heater unit of my 2013 Seat Leon FR. The unit is able to output heat but as soon as the fans are turned on (even when set to High), nothing but cold air comes out the Vents. My Garage has looked into the issue, but been unable to diagnose the root cause. They have removed the Dash and checked all the Blend Door Flaps are working correctly. They checked the Inlet and Outlet Hoses of the Heater Matrix and found that with the Heater controls set to ‘High’ both are too hot to touch, but when the Fans are turned on the temperature of the Outlet Hose drops significantly. They have replaced the Thermostat, which only really leaves an issue with the Water Pump or the Heater Matrix itself. They have taken the Car out on a long Test Drive and repeatedly driven it up a very steep hill to place the Engine under high load and the Temperature Gauge doesn't shift from 90 DegC, so they are doubtful it is an issue with the Water Pump. Given the car is only a year out of Warranty they are also doubtful it could be the Heater Matrix, but given the number of Heater Matrix problems I am reading about on here it looks as though it could be!

Hi

The internal heating matrix has its own circuit, so the matrix can be badly blocked and the engine circuit works away as it should. I'm a total numpty with spanners and managed to swap out the Matrix (Nissens part for about £80) in a couple of hours. I used the threads on here, the How to Guide to remove the glove box (buy radio pullers btw,) and then watched a video Skoda Octavia Heater Not Blowing Hot Air - Heater Core Replacement - YouTube You'll need a couple of Torx drivers (I accidently bought flexible ones, but actually was glad of it, when taking the fan blower off). I clamped the inlet pipe in the engine bay using a small G-clamp to reduce the flow and then made sure I had good polythene protection and old sheets to catch the outflow). Total cost was less than £120, including tools and coolant, plus my time. It takes a few uses to get all the air out after you top up, but a week later my Mk 3 (64 plate) is the warmest its ever been.

 

[hewittinspain]

Does anyone have instructions etc to replace the matrix via the glovebox on a 64 plate leon please

 

[UnHandyAndy]

Does anyone have instructions etc to replace the matrix via the glovebox on a 64 plate leon please

Hi,

Being non-mechanical, I did a lot of research before doing this job and couldn't find anything to confirm that the glove box can stay in place, so I followed:

https://www.seatcupra.net/forums/resources/how-to-remove-the-glovebox-media-unit.6/

and then used the video in my post above, to do the matrix.

I would recommend taking the glove box out to do this job. I see from your other posts you have a proper mechanic in tow, it should be a doddle for him. Good luck.

 

[hewittinspain]

Hi,

Being non-mechanical, I did a lot of research before doing this job and couldn't find anything to confirm that the glove box can stay in place, so I followed:

https://www.seatcupra.net/forums/resources/how-to-remove-the-glovebox-media-unit.6/

and then used the video in my post above, to do the matrix.

I would recommend taking the glove box out to do this job. I see from your other posts you have a proper mechanic in tow, it should be a doddle for him. Good luck.

Matrix was replaced yesterday and coolant flushed a few times. The drivers heating was all warm again but then ran cool yet again. If I switch off the heating for a few mins then it goes hot again and then runs cool. Not sure what to do?? Any advise

 

[BigJase88]

Matrix was replaced yesterday and coolant flushed a few times. The drivers heating was all warm again but then ran cool yet again. If I switch off the heating for a few mins then it goes hot again and then runs cool. Not sure what to do?? Any advise

Mine needed flushee multiple times, properly too hooked up to Seats machine. Probably partially blocked again

 

[hewittinspain]

Mine needed flushee multiple times, properly too hooked up to Seats machine. Probably partially blocked again

Do you think the coolant will continue to splurt out during a regen even though the matrix has just been changed(had to pull up twice on the motorway over the last month)? I can probably live with the heating issue as the cab still gets warm but its the coolant loss I hate

 

[BillyCool]

Matrix was replaced yesterday and coolant flushed a few times. The drivers heating was all warm again but then ran cool yet again. If I switch off the heating for a few mins then it goes hot again and then runs cool. Not sure what to do?? Any advise

It could be an air lock. It took a while for mine to settle down properly. I had to keep topping it up as the system is meant to self bleed over time and it should slowly purge the air.

If it's a new matrix and you've flushed the system best you can, I doubt it's blocked already.

Do you think the coolant will continue to splurt out during a regen even though the matrix has just been changed(had to pull up twice on the motorway over the last month)? I can probably live with the heating issue as the cab still gets warm but its the coolant loss I hate

It shouldn't - the new matrix should stop the overheat and coolant loss. If there is an air lock, it might still overheat though.

Once mine settled down I've not had to top it up in 12 months/8,000 miles.

 

[UnHandyAndy]

Matrix was replaced yesterday and coolant flushed a few times. The drivers heating was all warm again but then ran cool yet again. If I switch off the heating for a few mins then it goes hot again and then runs cool. Not sure what to do?? Any advise

HI,

See @Brian Gordon-Stables post below - that's exactly how mine went after the new matrix. I went old school and ran the coolant up to temperature with the cap removed, but it also needed a few decent runs out to settle properly (but has been fine since January now). I think others have hooked up the diagnostics and used the workshop manual to bleed the systems properly, but that's beyond me I'm afraid.

 

[SuperV8]

Do you think the coolant will continue to splurt out during a regen even though the matrix has just been changed(had to pull up twice on the motorway over the last month)? I can probably live with the heating issue as the cab still gets warm but its the coolant loss I hate

Are you sure the coolant expelled out the header tank (can you see coolant around the tank)? or maybe just air pockets purging - reducing your coolant level & triggering your low coolant warning?

With my blocked matrix mine only ever expelled coolant out the header tank after a long drive (with regen) when I stopped - so I would be greeted with a low coolant warning the next day. It never happened during a run.
These cooling systems are rather complicated, and just sticking a hose in the radiator won't flush them thoroughly, the official procedure something like is 2 or 3 flushes of each of the 4 circuits. If the matrix was changed before flushing you may find flushing has actually pushed more crud through the new matrix?
Could also be a faulty expansion tank cap?
Also filling should be done with a vacuum device - and even then there is an 'official' diagnostic bleeding procedure.

 

[Tay12345]

Hi guys just to confirm i had this issue.
1st i had no heat from vents so i changed matrix done coolant flush in the process got rid of the silly bag in the tank with silica beads.

After a week boom 1 side was hot 1 side was only warm and cold on high fan.

Changed various components made no difference so i again took the matrix out drianed coolant still had lots of bits inside suprising as i done a flush.

So i connected hose pipe to matrix pipes inside with a jubilee clip and ran it threw with a hose pipe. Cleaned out the matrix damn lots of big bits came out.

Put matrix back in jacked up the front end and filled coolant.

Now heating has worked better than ot ever has cant sit in the car with on full heat to hot.

Hope this helps. Just take your time flushing the system once will not do it if the beads have gone through the system

 

[Tay12345]

Mine needed flushee multiple times, properly too hooked up to Seats machine. Probably partially blocked again

Still bits in the system and matrix may take 2 to 3 flushes to force the beads out.

 

[Tay12345]

I had mine changed nearly 2 weeks ago for £180 labour and £70 for the matrix i supplied myself, and it solved the problem, hooray!..

BUT, I now have another issue!! The drivers side vent blows warm and not hot, I noticed that I used a tiny amount of coolant around 7 days after picking the car up after the drivers side vent was only blowing warm, then before i got round to topping it up, I did a short journey and noticed the drivers side vent was then only blowing cool air.. I topped up the coolant today and it has made it warmer/ on the verge of hot-ish but not back to how it was after the repair. Any ideas people.

Still bits in the system flush it again

 

[Tay12345]

Matrix was replaced yesterday and coolant flushed a few times. The drivers heating was all warm again but then ran cool yet again. If I switch off the heating for a few mins then it goes hot again and then runs cool. Not sure what to do?? Any advise

New matrix is blocked again. These systems take various flushes.

 

[RUM4MO]

@Tay12345, which engine type is in your car?

 

[chey.howson]

Hi all,

Just joined here as I too have a very similar issue to what's been discussed above.
I've flushed the coolant system completely (with a Forté flush and also connected a hose pipe to the header tank). I've replaced the heater matrix already (non genuine part) and I've removed the header tank with the silica bag in for a new tank. I've also completed a bleed through a diagnostic machine.
Still very intermittent heat, ofter freezing cold when driving but can get warm(ish) when stationary or slow driving.
I've just bought a genuine heater matrix.
Just wanted to see what others think as the garage seems unsure as to what it is. Thanks.

 

[BigJase88]

Hi all,

Just joined here as I too have a very similar issue to what's been discussed above.
I've flushed the coolant system completely (with a Forté flush and also connected a hose pipe to the header tank). I've replaced the heater matrix already (non genuine part) and I've removed the header tank with the silica bag in for a new tank. I've also completed a bleed through a diagnostic machine.
Still very intermittent heat, ofter freezing cold when driving but can get warm(ish) when stationary or slow driving.
I've just bought a genuine heater matrix.
Just wanted to see what others think as the garage seems unsure as to what it is. Thanks.

Probably just blocked up again with remaining bits of silica