It's been chilly enough in the last week or two that I've been trying to use the heater, but for some reason, even on the "HI" setting, it won't give me hot air. 

 

It just gives me slightly luke-warm air, and at the higher temp settings, it seems to invoke air conditioning which results in me getting even colder.

On the passenger side, it will blow hot air, but driver's side is always cold. This is whether or not it is in 'dual' mode with different temperature settings on each side or whether I take it out of dual and have the same temperature settings both sides.

 

Dual mode seems happy to blow *colder* air on the driver's side if I turn the setting to "LO", but not hotter air.

 

It's always been fine before, but a few weeks back I had a low coolant warning and then a new water pump as per this apparently common scenario.
So I'm wondering if that could be connected...? Or is it something else?

 

Sounds like the coolant system needs bleeding of air

 

 

Sounds more like an issue with one of the heater flap motors to me.

Yes flap motor/thermostat, had this problem several years ago with my first yeti, when on dual heat, the drivers side was artic and the passenger side tropical - repaired under warranty!

Edited 7 September, 20187 yr by Frenchtone

Thanks for that.
Flap motor sounds like a trickier/pricier fix then. (Sadly the car is out of warranty.)

 

I'd been hoping it was an air lock or something which could be bled out and linked to the water pump change.

But the different behaviour on different sides did make me wonder if it was something more complex.

Tried the calibration of the flaps?

 

 

Edited 7 September, 20187 yr by Plantman

11 hours ago, Plantman said:

Tried the calibration of the flaps?

 

Ah no - I didn't know that was a thing I could do.

Will give that one a go over the weekend then - thanks!

If you find somebody with VCDS you should be able to pin point the problem straight away. There is probably a code stored for the error as well.

47 minutes ago, SuperbTWM said:

If you find somebody with VCDS...

 

Ah...

Some years ago (just done a search and it was 2010) I joined in a group buy on this site, so I actually *have* a genuine Hex+Can cable.

 

Which I'd totally forgotten about until you mentioned it above.

 

But around the time I got the cable, my laptop started developing problems with the USB port dropping connection to external disk drives and such like.

While it's less than ideal to have a connection to an external hard drive drop in and out, I feared that a dodgy USB-to-VCDS connection could damage the car permanently or at least very expensively, so I never risked trying the cable.

 

I still have the cable somewhere, but never installed the software and not sure if I missed the chance to register it too. 

Would an 8-year-old, never used, cable still work...?

I can't see it being a problem other than if you are changing values and it disconnects, using it to do the tests on the flap motors or read codes it shouldn't be an issue.

 

If you have a genuine cable it does not require activation as the software is verified by the device itself so download the latest software and away you go

15 hours ago, SuperbTWM said:

I can't see it being a problem other than if you are changing values and it disconnects, using it to do the tests on the flap motors or read codes it shouldn't be an issue.

 

If you have a genuine cable it does not require activation as the software is verified by the device itself so download the latest software and away you go

 

Yes - as you suggested it does work.

When I first connected, it said the cable needed a firmware update - not surprising given the age - but once that was done it seemed to  work OK.

 

I was hoping that the auto-scan would reveal a fault code, but nothing showing (at least nothing that seems related to heating and ventilation).

So I've tried plantman's recalibration tip - I'll see whether that helped next time I'm out in the car and it's warmed up.

Beyond that I guess I need to read up on how to use VCDS..

58 minutes ago, DavidY said:

 

Yes - as you suggested it does work.

When I first connected, it said the cable needed a firmware update - not surprising given the age - but once that was done it seemed to  work OK.

 

I was hoping that the auto-scan would reveal a fault code, but nothing showing (at least nothing that seems related to heating and ventilation).

So I've tried plantman's recalibration tip - I'll see whether that helped next time I'm out in the car and it's warmed up.

Beyond that I guess I need to read up on how to use VCDS..

 

Doing the calibration via the front panel does the same thing only i'm not too sure how it would tell you if something was wrong or not.

 

Just have a look in the HVAC module on VCDS, somewhere in there you will find the output tests you can do, I can't really remember without looking myself.

Sounds like the crap I was dealing with where the various vents would only work depending on the temperature you were at. 

 

i.e. doesn't blow through the center vents if it was cold/hot to avoid blowing your face too much etc. 

 

Does it change depending on you selecting the manual orientation modes, i.e. feet, screen, face etc?

 

On 08/09/2018 at 20:17, gRoberts said:

Does it change depending on you selecting the manual orientation modes, i.e. feet, screen, face etc?

 

If I use those modes it still seems to be hot on the passenger side/ cold on driver's side.

 

On 08/09/2018 at 16:54, SuperbTWM said:

 

Doing the calibration via the front panel does the same thing only i'm not too sure how it would tell you if something was wrong or not.

 

Just have a look in the HVAC module on VCDS, somewhere in there you will find the output tests you can do, I can't really remember without looking myself.

 

Went back in to VCDS and it seems no new faults logged following the front-panel calibration thing. 

I also went into the mode which shows values of parameters, and tried logging values while changing the temperature dial on the panel. Here are a couple of values:

Address 08: Auto HVAC  (5E0 907 044 )

10:24:04
  IDE00976   Left front vent temperature 44.7 °C
  IDE00977   Right front vent temperature 32.0 °C
  IDE00998   Left temperature flap - actual value 99.5 %
  IDE00998   Left temperature flap - actual value 231 
  IDE00999   Left temperature flap - specified value 238 
  IDE01042   Right temperature flap: actual value 99.0 %
  IDE01042   Right temperature flap: actual value 231 
  IDE01043   Right temperature flap: specified value 238 

--------------------------------------------------------------------------------
10:24:57
  IDE00976   Left front vent temperature 43.0 °C
  IDE00977   Right front vent temperature 31.0 °C
  IDE00998   Left temperature flap - actual value 0.0 %
  IDE00998   Left temperature flap - actual value 25 
  IDE00999   Left temperature flap - specified value 19 
  IDE01042   Right temperature flap: actual value 18.5 %
  IDE01042   Right temperature flap: actual value 64 
  IDE01043   Right temperature flap: specified value 63 

As the "actual value" and "specified value" seem to be moving in sync for both temperature flaps, and no fault codes, I'm wondering if it could be an airlock/ bleeding issue after all?

Are there separate heater matrices (not sure of right term but whatever you call things containing water which the air goes through to make the air hot ) for left and right?

On 08/09/2018 at 15:51, DavidY said:

 

Yes - as you suggested it does work.

When I first connected, it said the cable needed a firmware update - not surprising given the age - but once that was done it seemed to  work OK.

 

I was hoping that the auto-scan would reveal a fault code, but nothing showing (at least nothing that seems related to heating and ventilation).

So I've tried plantman's recalibration tip - I'll see whether that helped next time I'm out in the car and it's warmed up.

Beyond that I guess I need to read up on how to use VCDS..

I think there is just the one heater matrix. 

 

What might of of happened is the flap has come loose or got stuck and lost drive. So the motor is moving and giving the correct position but the flap is still stuck shut or open(whichever way round it works) giving you cold air. 

Edited 10 September, 20187 yr by SuperbTWM

4 minutes ago, SuperbTWM said:

I think there is just the one heater matrix. 

 

What might of of happened is the flap has come loose or got stuck and lost drive. So the motor is moving and giving the correct position but the flap is still stuck shut giving you cold air. 

 

Thanks for that.
Sounds like a trip to the dealer is needed.

 

Thanks to @logiclee for these comments over on this other Heater thread.

Quote

 

There has been issues on the Mk3 with the gel back splitting in the expansion tank and blocking up one or more of the the three different water circuits.

 

 

Quote

Has anyone checked the silicon bag in the expansion tank as this could be the cause of the contamination. You will waste money if you have the system cleaned and this is still leaking.

 

After I'd posted above, I had the dreaded "Low Coolant" warning again.  When I left it with the dealer I mentioned this helpful theory and although the tech guy said he'd heard of it but never seen it before, when I spoke to him later, this did indeed seem to be the best explanation. 

 

I assume the order of events was:

• water pump fails (as a result of apparently common defect) and barely pumps any water around
• engine gets too hot as a result
• this causes the bag thing to split
• gunk goes round the system and, in my case, blocks the heater matrix on one side, and also causes poor coolant flow which presumably caused the second low coolant problem due to getting too hot again

They've swapped out the heater matrix and the expansion tank - hopefully there isn't other gunk left elsewhere in the system...

 

 

If the dealer had said hopefully there isn’t any gunk left elsewhere in the system would you be happy? I wouldn’t!

32 minutes ago, KevC_Derby said:

If the dealer had said hopefully there isn’t any gunk left elsewhere in the system would you be happy? I wouldn’t!

 

To be fair they said they've flushed it all out, but I'm perhaps being pessimistic.

Hi any help on this old post, I'm having same problem, Luke warm drivers side on Hi, passenger side good heat as normal.

vcds showing no fault codes 

it's freezing 

tried the reset calibration, same problem, drivers side only slightly warm 

Edited 10 December, 20196 yr by marco48

Unfortunately I'm now in the same boat. Tried the recalibratation last night but no luck

Hi everybody. iam a new member so i thought i'd let you know of my experience. my heater was blowing cold on drivers side but warm on passenger side.. ive got a skoda octavia 1.6crtdi estate. i mentioned it to skoda who was doing the timing belt and water pump at the time. are you all sat down lol. they quoted me £1700.00. they said your heater matrix is partially blocked and it takes around 8-9 hrs . mainly the cost is the amount of flushes it has to have which is mainly labour. i,ll keep this as short as i can. skoda was right. heater matrix partially blocked. everybody who has similar problems ? just try this if your not sure ? put heater on full and speed on full ? cold air i guess. now keep heater on full and fan speed at number 1 or 1st notdge. mine started slowly blowing warm air ever so slightly so that would probably indicate a partially blocked heater matrix. and then when switched to full it went cold. anyway i had a new heater matrix fitted and now blowing hot air perfect. ive learned from guessing myself and thinking its this or that or this or that. i myself pay and wouldnt hesitate at paying £90 for a skoda technician diagnostic to tell me whats wrong with my car even though you might want to do the job yourself or even local mechanic because of labour costs. there normally always right and i suppose if you were to let skoda do any repair at least you get a guarantee/ warranty. thanks

I had the same issue two years ago on a passat b6, only it was warm on the driver side and cold o the passenger side. I tried everything I could try by myself, resetting the flaps from the climatronic button combination, that did not helped. Then a friend of mine told me that it's possible that the ventilation flaps located under the dashboard on passenger side is stuck, so I bought a brand new one. That also did not solved the issue. Later on, I discovered that I was loosing coolant, but without seeing anything under the car, so I took the car to a service and they discovered that the heater core pipes were twisted and the heater core was blocked or something. Its location was new the pedals on the left side. After they changed it, problem was solved. So I would suggest that you check the floor near the pedals and see if you find leakage there,thenthe heater core would be the next thing to check.

I'm new to Octavia Mk3 ownership but it looks like the heater blocking is a common theme on VAG cars with the silicon bag. I have read many issues on here from people with the same problem. whilst some will be possibly a fault with a servo flap on the dual climate system, many seem to be related to the matrix blocking and causing the problem. I have done mine and i have written this up and it can be found in the guides section. It took approx 3 hours (book time is 1.5hrs) and the parts can be sourced very cheaply without going to the main dealer. When i removed the old matrix i thought i would find it totally blocked. This isn't the case as i could still blow through it and i could get it to pass water through albeit very differently to the new matrix. I have been told by a local radiator specialist that they sell loads of these matrix's and they have tried to flush them with no luck as they claim the cores are very thin and will block up very easily. If you are confident and handy with a few tools i would say give it a go and save yourself hundreds? of pounds. I quite enjoyed doing mine and would no hesitate in doing another.

 

hope this helps

Hi, did you change the expansion bottle and did you replace or remove silicon bag?