[Closed] Skoda Octavia - cabin heater gets cold over time?????

Blockage in the heater matrix innit. Hot water flows through from the engine to a thing like a radiator behind the dash when you want heat. However, when cruising on the motorway I suppose there's less hot water to spare since the engine's cooled better...? If it's gradually getting colder then it would really point to not enough water flowing in there.

Try flusing the system.

Are you saying the blower isn't working, no air or is there plenty or air it just ain't hot? Your OP isn't clear.

Have you got dual climate? I have had this exact problem it was a temperature sender for the Air con outlet. It stops sending and the outlet freezes up so air is unable to come in to the car.

If it works OK with the air con off (in ECON) then I'd put £50 on it being this.

Mine didn't show up as a fault on VAG.COM so I forced them to look at it by driving it for enough time for it to freeze up. Fortunatley it was fixed under warranty for me but its a dashboard off job so don't expect it to be cheap labour

It even stops sending (much) air out of the vents. I can hear the fans loudly but they're not achieving much.

Have Aircon but not climate control. Manual controls for where the air goes.

oh - and aircon makes no difference on or off.

I thought maybe somehow it is blocking the air inlet, somewhere before the fans, when the car is warmed up and travelling fast?

Something blocking the air intakes? Could be something that gets pushed with the air pressure at high speed, but not a lower speeds?

good point - I'll go take a look!

Oh - where's the air intake on an Octavia anyone??? lol

Might it be as simple as this?:
With the severe cold this winter, I found that running the heater hot was actually taking so much heat out of the cooling system that the gauge was not even getting off the minimum temp end of the scale.
This was in a Mondeo diesel.
It was only really noticable when coasting down a long hill or chugging along slowly. Making the engine work a bit soon got things back up to temp and the aircon responded accordingly.

if the air coming from the vents is hot & powerful on full fan speed when travelling in slow traffic all appears ok yes? when speed increases the air from vents gets colder but still powerful then it sounds like the thermostat for the cooling system is stuck open. if the fan is on full but air coming out isn't powerful but noisy the pollen filter could be blocked (this doesn't affect heat output though)

if the air coming from the vents is hot & powerful on full fan speed when travelling in slow traffic all appears ok yes? when speed increases the air from vents gets colder but still powerful then it sounds like the thermostat for the cooling system is stuck open. if the fan is on full but air coming out isn't powerful but noisy the pollen filter could be blocked (this doesn't affect heat output though)

Rachel - will you let us know what caused it when you find out, as we have the same car?

Thanks

will do - still trying to work it out. Strangely, I've just had to have the new fridge/freezer repaired as the fan has broken in it. Weird coincidence???

Oh - and thanks for sorting out the bag for my brother to give me - it's gorgeous!!!

Rachel

Check Fluid level
Thermostat

Fluid good.

Not sure how to check a thermostat?

Adscatt beat me to it...I vote that the thermostat is stuck open, so coolant is always flowing through the rad, at high speeds this will mean the engine is being over-cooled.

If you start the car from cold and leave it idling or (if its a diesel and you can't spare the hour it'll take to warm up) take it for a short drive but stop before the temp gauge gets to its normal position, then let it idle. Keep checking the rad, if it gradually warms up before the gauge reaches its normal position, then the thermostat could be stuck. Normally the rad will stay cold until the engine is nice and hot, then the stat will open and the rad will get hot within a minute or so. Keep fingers clear of the fan as it may start as the engine gets up to temp, particularly if the climate control is on.

You can also remove the stat and drop it in a pan of boiling water to see if it reacts, although this involves a bit of spannering it will give you a definite answer. Easy to remove after draining the coolant but could be difficult to get to on a modern car. I'm sure someone will correct me but I believe its normally where the upper hose to the radiator leaves the engine block. You will need a new gasket or a tube of liquid gasket to reseal the stat and prevent water leaks.

The other possibility is an air lock, the heater matrix tends to be the highest point so this could cause lack of heating. But I wouldn't be able to tell you why the air lock manages to clear itself, normally it would need bleeding.

cover the radiator with a piece of card or kitchen foil, and see if that works, work transit i used to drive had the rad covered up all winter, then the new muppet decided to drive at 30 everywhere, in the cold, and succeeded in over heating the engine, due to lack of cooling air.

Surely the muppet is the person who covered the rad?!

Oh - and thanks for sorting out the bag for my brother to give me - it's gorgeous!!!

Aww thanks (blushes).

If you're not getting any airflow out the vents, then it's not going to be the thermostat.

Try removing the pollen filter, and see if things improve.

Although.. Skoda of that vintage might have what VAG called climatronic which is thermostatically controlled hot/cold air but not full climate control. On my Passat of that age (and before, on my 2003 Seat too) there are numbers on the hot/cold dial from say 18C to 28C. So perhaps the thermostatic system is shutting some duct expecting the air to be hot and it's not..

Just a thought.