Sudden misting/fogging up issue

[cbanwellclode]

The background is that I've had my 2008 Octavia Estate from new and never experienced any damp problems or fogging up.

 

Today I've driven a 5 hour trip and as soon as I started all of the interior windows misted up very badly. It was a cold, between 2 and 5 degree evening, but clear and dry. Increasing output from the heaters/fan on only made the misting up worse. I could open the windows the clear the mist, but as soon as I put the fan on you can see them begin to mist up. I was alone in the car, and there was nothing such as a wet coat to cause this. This is not the usual problem of taking a while to demist. After hours of motorway driving I'm having to open the windows to clear the windscreen. The windows are dripping after the trip.

 

The fan is working fine and can blow hot air. The Air Con needs a regass, but it's been like that for a few months so I don't think its related, although it would obviously help.

 

The car interior, carpets, seats, boot floor are all dry.

 

I stopped and removed the pollen filter, but this seemed dry and running without the filter made no difference to the problem.

 

This may be my imagination, but a couple of times as I traveled down hill the misting appeared to get better.

 

I can't see any water in the scuttle.

 

From what I've read there are three things to check:

(1) Is it stuck in recirculate mode?

(2) Is there a leak at the heater matrix?

(3) Is the air con condensation outlets blocked?

 

For (1) Is there an easy way to tell if the ventilation is stuck in recirculate mode? Would the recirculate mode really cause this much of a problem?

 

For (2) is it easy to see the matrix. The condensation on the windows did not appear to smell of coolant so I'm hoping its not this.

 

For (3) is there anywhere to check for a blockage from the air con system? As its currently not working that well I'm not sure if I'd see much dripping out after a run at the moment.

 

Any ideas would be appreciated.

[cbanwellclode]

I've just tried doing a flap reset, and I can hear some motors whirring. 

 

Can anyone tell me if with the ignition on and the fan running low, when pressing the recirculate button should I hear a flap operating?

[Guest]

Yes, you should hear the system reconfiguring any time you (de)select any vent distribution options and the fan/ambient sound levels are low.

 

With the fan on max you won't hear the distribution mechanism however you should definitely hear a change in the flow of air when you toggle the recirc button.

[cbanwellclode]

Thanks MicMic, that's what I thought. I also thought that you could hear a change in airflow when recirc. was on,  a slightly muffled effect if you know what I mean.

 

The light on the recirculation button does come on and off for me, does anyone know if this confirms that there is not a fuse related problem, i.e if the fuse that controls the flap motor was faulty then the light would also not work?

 

Does anyone know which fuse control the reciirc. flap, and what else that  fuse that controls? 

 

Finally, when performing a flap reset operation (holding the "Econ" and "Face Flow" buttons for 3 seconds), is the information displayed on the climate control temperature displays meaningful, i.e. does it display an error? 

[cbanwellclode]

This is the only output to the temperature display when I request a flap reset. Does anyone know if this is correct, or should it update as it cycles through the flaps?

 

I seem to recall that doing the flap reset used  to take several minutes, but mine is now only taking about 20 seconds.

[Guest]

The flap reset sequence if that is what it is called takes approximately 20 seconds on my car and displays the same hieroglyph.

 

I can't comment on fuse at present.

[cbanwellclode]

Thanks MicMac.

 

[TheClient]

13 hours ago, cbanwellclode said:

The background is that I've had my 2008 Octavia Estate from new and never experienced any damp problems or fogging up.

 

Today I've driven a 5 hour trip and as soon as I started all of the interior windows misted up very badly. It was a cold, between 2 and 5 degree evening, but clear and dry. Increasing output from the heaters/fan on only made the misting up worse. I could open the windows the clear the mist, but as soon as I put the fan on you can see them begin to mist up. I was alone in the car, and there was nothing such as a wet coat to cause this. This is not the usual problem of taking a while to demist. After hours of motorway driving I'm having to open the windows to clear the windscreen. The windows are dripping after the trip.

 

The fan is working fine and can blow hot air. The Air Con needs a regass, but it's been like that for a few months so I don't think its related, although it would obviously help.

 

The car interior, carpets, seats, boot floor are all dry.

 

I stopped and removed the pollen filter, but this seemed dry and running without the filter made no difference to the problem.

 

This may be my imagination, but a couple of times as I traveled down hill the misting appeared to get better.

 

I can't see any water in the scuttle.

 

From what I've read there are three things to check:

(1) Is it stuck in recirculate mode?

(2) Is there a leak at the heater matrix?

(3) Is the air con condensation outlets blocked?

 

For (1) Is there an easy way to tell if the ventilation is stuck in recirculate mode? Would the recirculate mode really cause this much of a problem?

 

For (2) is it easy to see the matrix. The condensation on the windows did not appear to smell of coolant so I'm hoping its not this.

 

For (3) is there anywhere to check for a blockage from the air con system? As its currently not working that well I'm not sure if I'd see much dripping out after a run at the moment.

 

Any ideas would be appreciated.

 

I think those three are logical things to rule in or out.

 

Not sure how easy the heater matrix is in the OctII but most newer cars they are pigs to get at. it maybe more feasible to empty it and block the lines  to it (engine end) if feasible, during warmer weather to rule it in or out, but you should see some coolant loss eventually if it is leaking. A tiny leak could take quite a while to notice the level drop though.

 

Other possibly is water ingress somewhere you haven't noticed or checked. The OctII has quite a few water ingress issues like around the front door seals but you say the carpet is dry.  If you could make sure the sublayers are as well.  Also, check other places like spare wheel well etc.

 

When I change my car to recirc is does show some misting quite quickly and that is with air con operative (climate control).

 

Air con does help being a dehumidifier as well but if yours has been inoperative for some time and you have noticed this step change it seems unlikely to be the cause.

 

 

[Tilt]

If, as you say "the fan is working fine and can blow hot air", then the recirc flap must be working, or at least open.

Therefore it would usually clear at least as the air warms up.

 

Is warm air not clearing it, but making it worse? very unusual.

 

Is the fan actually blowing hot air onto the windscreen?????????

 

I do have this issue a lot until it warms up. I use wind/rain deflectors so i can keep the windows cracked open a little but not worry about it raining.

[cbanwellclode]

Thanks TheClient for the advice.

 

[cbanwellclode]

Thanks Tilt, but why do you think blowing hot air relates to the re circulation? I thought the Recirc - ON simply stopped air from outside entering the system. i assumed that whether it is on or off should still produce hot air, be that air from the outside being warmed by the heater matrix (with recirc OFF), or air from the car being reheated by the matrix (with recirc on).

 

Or am I misunderstanding it, and the air being blown with recirc on, doesn't get re-warmed by the matrix, so with recirc ON the car temperature will slowly drop?

[Tilt]

^^^ Good question.

It was my assumption that recirc kept the same air inside the car without it being warmed by the engine

 

Or was it my assumption, Lol.

[Guest]

Recirc simple blocks off the inlet of fresh air and instead the fan recirculates the interior air.

 

This does not affect the heat/AC setting, simply where the source air is coming from so heating/cooling will be faster at the expense of freshness as if left on recirc for extended periods the cabin will become stuffy.  However with AC on the interior air will dry quicker as it progressively loses moisture to the evaporator.

[cbanwellclode]

This morning I took off the side panel from the passenger side dashboard, hoping I could get a glimpse of the Recirculation flap behind the glove box, without actually having to remove the box. I'm not certain, but I think I could see the flap and pressing the recirc button didn't move it. I could just about get my fingers to it and managed to open it, so I'm hoping this may be a workaround. If it avoids the misting up I'm happy to live without the re circulation facility.

[Tilt]

On 1/6/2018 at 16:43, cbanwellclode said:

Thanks Tilt, but why do you think blowing hot air relates to the re circulation? I thought the Recirc - ON simply stopped air from outside entering the system. i assumed that whether it is on or off should still produce hot air, be that air from the outside being warmed by the heater matrix (with recirc OFF), or air from the car being reheated by the matrix (with recirc on).

 

Or am I misunderstanding it, and the air being blown with recirc on, doesn't get re-warmed by the matrix, so with recirc ON the car temperature will slowly drop?

 

Try another way then, kind of in reverse...........

 

Let the car warm up with heat coming through the vents whilst driving along.

Then turn the controller to cold, with the air con disabled (econ on) and recirc off and see if the incoming air turns cold from the cold outside air. 

 

If it does then the recirc flap is open. Turn the recirc button immediately on and if it stops the cold air then it is closing too.

 

[Guest]

As said previously, the change in fan sound at max is easily discernable when toggling between recirc/fresh.

 

If you suspect it isn't functioning, try putting it in reverse gear.  The recirc function automatically activates to lessen exhaust gas ingress.  Again the sound the fan makes is noticeable.

[cbanwellclode]

I looked again and realised that the flap that I could move without taking the glove box out was the "air direction flap" not the re-circulation flap, although they are both linked to the same motor.

 

Just to finish the thread off, the car was in for a service today so I asked them to take a look at the air re circulation flap. As I expected the motor was broken and left the flap stuck shut (not letting any fresh air in). To save the expense they simply opened the flap and disconnected the motor. I'm happy with that, and the fogging up is now fixed.

 

Thanks for everyone who has given advice.