heater problem

[franky65]

Hi,i have now got a heating problem,temp normal but cabin only cold air blowing

any help would be appreciated.

thanks.

[ords]

You could try re-calibrating it.

 

[PetrolDave]

Failing that could be an airlock (had any work done recently on the cooling system?) or a stuck servo that controls the temperature flaps in the HVAC.

[Boatman1]

Could be a blocked heater matrix, have you used radweld or similar in the coolant system? If not, check the colour of the coolant in the reservoir, is it normal, do you have a silica bag in the reservoir? is it intact? Let me know because I have had the same problem and still haven't solved it despite two heater matrix being replaced, both blocked, recently had a coolant flush still hasn't sorted it and my heater is now running cold again. Are you losing any coolant?

[franky65]

no radweld used,water very brown,and car going to garage friday morn,

mechanic seems to think that the coolant pump may be faulty,we will see.

i have asked him to backflush system.

[franky65]

had mechanic look at prob and told me someone HAS used rad weld,he flushed system out

and water running through matrix so so,refilled with new coolant,so now will see, going back 

in next week to have new cam belt/aux belt/water pump fitted.

will see then if it runs hotter.

[MikeDMikeyDarby]

Hi Franky65

How did you get on with sorting your space heater? When its really cold outside, my Octavia takes 30 minutes before I get warm air coming into the cabin.

[Noms]

This might sound like  a silly question, but are you pressing the buttons to direct the air?

If not, then press the buttons for windscreen or passenger facing etc and see if the temperature increases.

If you leave the fan on with out directing the airflow, it an be of different temps.

 

[cheezemonkhai]

On 04/12/2021 at 07:14, franky65 said:

had mechanic look at prob and told me someone HAS used rad weld,he flushed system out

and water running through matrix so so,refilled with new coolant,so now will see, going back 

in next week to have new cam belt/aux belt/water pump fitted.

will see then if it runs hotter.

Are you sure it’s radweld and not a split silicate bag from the header tank?

[MikeDMikeyDarby]

14 hours ago, Noms said:

This might sound like  a silly question, but are you pressing the buttons to direct the air?

If not, then press the buttons for windscreen or passenger facing etc and see if the temperature increases.

If you leave the fan on with out directing the airflow, it an be of different temps.

 

As a professional Welding & Quality Engineer I know there are no silly questions,  so I thank you for your input. It was commuting just after storm Arwen when ambient temp was around zero. I tried selecting the different combinations of the air direction zones & checked air was being directed as selected. I  tried also selecting the AC system, as a previously owned new Kia Sportage GT Line had a supplemental heater in the AC system. Unfortunately my Octavia AC output seems to have no discernable  effect on heat output!

Once again thanks for your question.

[franky65]

had a new cam belt/aux belt and water pump fitted.Pump was near seized and was very worn.

it had k-seal put in by someone as the water although brown ,had flecks of copper in it.

temp gauge taking at least 2 miles before any semblance of heat coming through.

next to change will be thermostat.

But it still looks like a new matrix needs fitting.

Watch this space.

[cheezemonkhai]

2 miles is pretty normal for a diesel as they're much more efficient than a petrol car, so generate less excess heat.

I'd give it a week or two before you go changing parts.

 

If you're chaning the parts, change the header tank, just in case the silica bag/tube has split. It's so cheap it's not worth making a mess of a new matrix for the sake of the tank.

[J.R.]

I would say that they have fitted a pattern part waterpump that does not have the problematic electrically operated impellor shroud, your car is indeed displaying typical diesel warm up behavior but the shrouded water pumps when they function bring cabin heat through much earlier and reduce the time before the thermostat opens.

 

I believe there is also an auxiliary electric coolant pump to circulate warm water through the heater when the main waterpump is shrouded, that is something else to look at.

 

The VAG self study guide for your engine gives full details of how the system operates during the warm up phase, good diagrams, does a much better job than I ever could.

[franky65]

thanks for the advice and all of your help,much appreciated.

Frank.

[Ecomatt]

8 minutes ago, franky65 said:

thanks for the advice and all of your help,much appreciated.

Frank.

 

If you watch this video from about 12:00 mins onwards, it tells you how the coolant circuits work as there are a few.

[J.R.]

Interesting, a shame they dont use technical translators as some of the terms dont make sense until you make the connection, duct = port etc, also "charged" means something else like "in operation".

 

What a truly overcomplicated piece of kit and its not even EU6 😲

 

I learned somethibg right at the end, the silicate teabag in the header tank is a preventative measure in case the system is filled with water and not G13 coolant. Mine looked like brown water recently, I removed the radiator, intercooler etc to replace the crashbar nearly 2 years ago and it looks like I refilled with water and forgot about it, 2 x 5 litres of G13 concentrated should arrive today, I was lucky last winter by the looks of things although I did  buy and use a pen coolant tester.

[paulski]

Great video, love the fact at the end they discuss the ticking time bomb "MIT Silikat"

 

Roughly translated it means,  we made our engine so sensitive to corrosion we had to stick a plastic bag of special crystals in the expansion tank that, in about 5 years time, will split and block the heater matrix😄

Edited 9 December, 2021 by paulski

[J.R.]

The aluminium alloys used are no more sensitive than any other manufacturer, it is typical VAG attention to detail that they added the Silkat to counter corrosion if the system were to be filled with plain water (assuming that they are not telling porkies), trouble is they have been bit on the bum for it.

 

 

[cheezemonkhai]

The original design was IMHO far more resilient than the more familiar tea bag style design.

[J.R.]

Mine does not have the silkat marking and no evidence of a teabag which is why I am concerned to relace the coolant because it looks like I may have topped up half the system with tap water 18 months ago or used some glycol anti-freeze that I had on the shelf.

 

Still waiting for the Ebay seller delivery, its always the stuff you need that is the slowest delivery.

[MikeDMikeyDarby]

On 01/12/2021 at 09:12, ords said:

You could try re-calibrating it.

 

 

[MikeDMikeyDarby]

I gave this calibration technique a go and it definitely worked on my 2016 Octavia. It's surprisingly easy to perform and after calibrating twice, now I have heat in the cab in 2 minutes. Brilliant!!!