Hi All,

 

FIrst post, so be gentle!

My Mum's Skoda Octavia only blows cold air out of the in-car blowers; I have just flushed the entire coolant system, using coolant flush and then a garden hose until only clear water was coming out of the radiator, engine, oil cooler, and heater matrix pipes.

The car is now getting to temperature properly (gauge reads 90C) and all hoses are gettting hot, including both heater hoses, but the blower inside the car still only blows cold, even when the heater setting is on High (and at every other setting). Is there some sort of flap or electronically controlled valve that could be the issue?

 

Many thanks, John

Further to my originl post - I have remembered that bits of foam have been blowing out of the eye level air vents (presumably it is the foam that covers the mixture flaps) - would this account for the lack of heat, and if so, how easy is it to replace the foam / is there a better tape to use to cover the flaps. Also, if recovering the flaps will sort it, how big a job is it, i.e. can it be done without removing the whole dashboard, as I had to do that to replace the heater matrix in my old Polo and it was a nightmare of a job?

Assuming the car is an Elegance as per your signature, it has climate control. The various flaps to control air flow and temperature are motor driven. It is a simple answer so try to find someone with VCDS near you to diagnose the fault. Flap motors can be changed with out removing the dash, however some take quite a bit of finding. The motors are the same as Mk4 Golfs so specialist VW breakers can be a source of parts,

 

1 minute ago, krisp1 said:

Assuming the car is an Elegance as per your signature, it has climate control. The various flaps to control air flow and temperature are motor driven. It is a simple answer so try to find someone with VCDS near you to diagnose the fault. Flap motors can be changed with out removing the dash, however some take quite a bit of finding. The motors are the same as Mk4 Golfs so specialist VW breakers can be a source of parts,

 

Also @krisp1 - First step here is actually 10 minutes of flapperobics; get the engine hot (say 20 minute drive) then spend 10 minutes playing with all the Climatronic panel controls, particularly the temperature settings, recycle and demist control.. This has a fair chance of unsticking flaps.

Read the attached it explains the Climatronic system.

Depending on your level of knowledge it may blow your mind or all may become clear.

There is a function in VCDS to set the flaps in the correct position. The output from the potentiometers need setting for correct function.

SSP+25+Octavia+climatronic.pdf

Thanks for all the advice, I have got VCDS (Ross-Tech I think) on my old laptop, so will plug that in and have a look. I think I can hear the flap motors when I press the different setttings buttons, so my suspicion, given all the bits of dry foam coming out of the vents, is that the air is going straight through the flaps (assuming they are metal flaps with holes in them, like on later models) rather than redirecting the air through the matrix.

On 07/12/2023 at 16:48, krisp1 said:

Read the attached it explains the Climatronic system.

Depending on your level of knowledge it may blow your mind or all may become clear.

There is a function in VCDS to set the flaps in the correct position. The output from the potentiometers need setting for correct function

Thanks for that detailed document - I have plugged in my ODBC and found no error codes in relation to the heater system. My theory I think is the correct one - i.e. that the foam covering on the flaps has disintegrated and is not directing the air through the heater matrix  (as highlighted, below);

If you plug in a generic OBD code reader you will not get any error codes for air con, brakes etc.

The OBD standard only covers engines.

You need a dedicated VAG code reader to cover all the systems on a VAG car.

Am I correct about your code reader?

 

This is the read out from VCDS when I had problems with the flap motor on my car.

 

The codes are specific to VAG cars.

I'm fairly sure the software I have is genuine VAG, as I have had braking system fault codes reported on it in the past, but it is not currently showing any faults.

The ringed item is the flap. The foam seals on these are quite narrow and if they fail they will not cause a lack of heat.

Fundamentally the air is not flowing through the heater matrix which means the flaps are not moving.

I am not convinced you are using a suitable diagnostic code reader to find the errors.

The effort of dismantle the heater unit is huge. You need to find someone with VCDS to check for codes. Also when the servo motors are replaced VCDS will initialise them to have them correctly set up.

The servo motors are mounted on the outside of the heater unit, they are not easy to get to, but are less work than splitting the heater unit.

I also had the foam desintegration issue, and what it does is that there is no proper air sealing when the flaps are closed. Meaning that you will close air to specific vents, and there will always be a small amount of air being blown. IMO, that won't, however, affect temp changes. 

 

I would check for a clogged heater matrix. Just flushing the coolant system might not be enough (been there, done that). Overtime, dirt accumulates inside the heater matrix narrow passages, preventing water from circulating. Despite the hoses getting hot outside, water won't flow. If this is the case, unplug the hoses and try using compressed air (carefully), in the opposite direction of water flow; also be careful with the valve described in the paragraph below, that needs to be open. 

 

There is another possibility. The temperature is regulated by a vacuum operated thermostatic valve (controlled by the temp setting), located in the motor compartment, in the heater matrix exit hose. I believe this type of heat control started being implemented during year 2000, so older models might not have it. If the air operated diafragm has ruptured, or there is a vacuum leak, there will be no temperature changes, as the valve won't operate. You can easily test the valve applying vacuum, as you can listen to it open and close. 

 

In either case, however, and despite water flow is blocked (by a clogged heater matrix or a non functioning valve) you could perhaps feel a mild temperature change in the air leaving the vents, as heat propagates through conduction to the heater matrix. One easily assumes that there are no temperature changes, as it takes a very long time for heat to reach the heater matrix, and any effect, however minor, to be felt. 

A vacuum operated thermostatic valve  is only relevant for cars with manual AC control. Climatronic as in this instance does not have a vacuum thermostatic valve.

I have climatronic in one of my cars, and that valve is there for me to see (AVU motor). As I said above, had to open it in order to be able to unclog the heater matrix. 

Bear in mind Iberian market cars may be a different specification to UK cars.

The English language Climatronic documentation do not mention the valve you mention.

Do take a look at SSP 222, page 16; the vacuum operated valve is mentioned there.

 

SSP_222_Electronically Mapped Cooling System.pdf

As the document states it was introduced on the 1.6 petrol engines you have. The implementation was a major change and the 1.9PD engine probably was not engineered for it.

It does not appear on the CAYC 1.6tdi engine that replaced it as far as I can tell.

Valve N147 is also mentioned here. Actually, what is pointed out in the drawing is the electrical control of valve N147, that will allow vacuum to be applied as needed. The valve

 

https://workshop-manuals.com/skoda/octavia-mk1/heating_air_conditioning/heating_air_conditioning/heating/repairing_heating_system/2_way_valve_for_coolant_shut-off_valve_n147/

 

2 minutes ago, krisp1 said:

As the document states it was introduced on the 1.6 petrol engines you have. The implementation was a major change and the 1.9PD engine probably was not engineered for it.

It does not appear on the CAYC 1.6tdi engine that replaced it as far as I can tell.

 

I have that valve in my AVU motor, not in my AKL motor. AVU has an electrically controlled thermostat (along with other modifications), thus the reason for having valve N147, as I read somewhere. I´m not aware if such a system was used in other motors..

 

The important here is that @Octavia04TDi is aware of such possibility.

Hi all

I have the same issue but would this be relevant from the vcds print out?

Starting to get chilly in the mornings now and no heating in the car... Any clues how I should proceed to get the heater working please?

Has the goal on the internal flaps disintegrated and started blowing out through the vents? That's what happened to mine and it is a case of having to replace the foam with metallic tape so the air is directed over the heater matrix. I didn't replace it as it is likely to be scrapped soon anyway.

Another feedback on clogged heater matrices, related to insufficient heating.

 

About a year ago I had to unclog the heater matrix in my Octavia with an AVU motor, as described in one of the above posts. Symptom: no heating inside the cabin.

 

Last week had to do the same to my other Octavia, this one with an AKL motor, that for quite some time had the same symptom: no heating whatsoever inside the cabin. This time it was simpler, as there is no vacuum operated valve to control the temperature. Just had to disconnect both hoses entering/leaving the heater matrix, and gently blow compressed air on one side. It was a delight to see all the gunk coming out and, after a few bursts, feeling air flowing freely across the heater matrix.

 

I haven't tested it yet, as there are a few other pending issues to solve, but I believe all will be well now.