UK-POLOS.NET - THE VW Polo Forum

Folk,

I've had my Polo now for almost 3 years (it's out of warranty as preregistered), it's a 2017 GTi.

Around 6 months ago I had a coolant leak and VW replaced the thermostat housing where the leak was coming from.

As it's now winter and much colder, I've noticed that I get lukewarm hot air out the heating vents at best, it was better in summer but then the ambient air was much warmer.

The thermostat seems to be operating correctly with the system heating to 90 quickly before the rest of the pipes start to heat up.

The heating resistor is operating correctly, with all fan positions working as they should.

The actuator for the hot to cold also works correctly.

I'm wondering if it's a blocked matrix but thought it may be a bit too young for that?

Any other suggestions before I go diving in about that?

Thanks in advance!

G

Sounds like to me there maybe an air lock in the heater matrix causing you to get just a small amount of heating.

Dink wrote: Thu Dec 03, 2020 9:56 am Sounds like to me there maybe an air lock in the heater matrix causing you to get just a small amount of heating.

My thoughts too...

Thanks folk,

I've tried to bleed air and not sure how well I've gotten on with it yet, one thing I do now notice is that my left centre and far left vents are putting out much warmer air, meanwhile the right centre and right vents are still cold...

Is this likely due to it being the airlock issue?

Cheers

The system, given time should purge out all the air on most engine designs, that is part of the reason that some coolant gets returned to the header tank in normal running.

Does your header tank have "Mit Silikat" printed on the side of it, if so you could have a "tea bag" type container in that header tank containing silicate granules and maybe that bag has split open and choked one side of the heater matrix?

Rum4mo,

It does indeed have silica, just checked the bag and it looks like it's still fully intact....I hope!!

See what happens when I take it a run tomorrow

Cheers

Why some cars have the tea bag type container of silicate granules and some don’t remains a mystery to me.

My previous car was a 2016 Polo GTI, so a few months older than the OP’s GTI. Cooling system had G13 coolant. Mine didn’t have one of these bags in the cooling system expansion tank and I was fortunate not to have any issues with poor, uneven (or lack of) warm or hot air distribution from the heating vents during 4.5 years of ownership.

@SRGTD "Why some cars have the tea bag type container of silicate granules and some don’t remains a mystery to me."

This for me as well is a joke, really some good firm hard facts need to be stuck together that can answer all these types of questions.

Which engine, which fuel type, which coolant, when fitted - and a big why!

Edit:- I've read lots of what are only suggestions on SEATCUPRA but nothing that has been good enough to stop me diving back in and asking more again and again.

My current interest is my daughter's May 2019 Leon Cupra and also when do I need to consider replacing coolant that has no official "replace" service details.