Author Topic: Steaming up on "recirculate"  (Read 3257 times)

Offline andyb_123

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Steaming up on "recirculate"
« on: 18 March 2018, 17:58 »
We occasionally press the recirculate utton (when going through a tunnel or following a car with a cloud of blue smoke behind it).

We notice doing so causes the interior to start fogging up, which is really annoying. It's happened a few times.

Our old MK5 never had this problem. Is this common in Mk7s?

The aircon is usually left on 'auto'. Sometimes I'm driving in "normal", sometimes in "eco".

Offline 2007GTI

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Re: Steaming up on "recirculate"
« Reply #1 on: 18 March 2018, 18:35 »
that happened for me on my mk5 and my mk7. if its on eco, it won't be performing fully, so I would leave it on normal.
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Offline fredgroves

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Re: Steaming up on "recirculate"
« Reply #2 on: 19 March 2018, 07:49 »
If you are in "eco" the aircon is set to super low and probably can't even clear the windows.

Why are you using eco? It absolutely saves bugger all fuel. Don't be fooled by it!
Current: Mk8 GTI DSG, Adelaides, DCC, HUD, HK, Winter Pack, Rear Camera.. Aka "HMS Weasel"

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Offline andyb_123

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Re: Steaming up on "recirculate"
« Reply #3 on: 19 March 2018, 17:10 »
I use eco if doing a boring slowish motorway journey. It's the only mode where "freewheeling" happens, which does seem to use less petrol than when in normal - on some stretches, the car's basically idling for a mile or so. If I need a quick burst, I stick the DSG into sport mode for a bit.

I usually have it in sport mode for country lanes or whatever.

The fogging up happened with the car in "normal" mode, so the aircon wasn't in low power mode, though it was about -2 outside. The first time it happened (going through the Rotherhithe Tunnel) it was a bit scary as the lanes are ridiculously narrow and stabbing at the controls took my eye off the road.

The MK5 never did this to us. It would use the aircon to remove all the moisture when recirc was on, which is what I'd expect with the MK7 too. It's the only thing about the car which is a regression from the MK5.

Offline dubber36

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Re: Steaming up on "recirculate"
« Reply #4 on: 20 March 2018, 08:05 »
Recirculate doesn't let any fresh air into the car. This is needed to draw air through the car, taking moisture with it. At this time of year the car will have more moisture in it due to wet shoes and coats, so not allowing fresh air in will cause the condensation.

Cars, like new houses, are so well sealed these days that air doesn't move around freely. In the old days the draft under your front door would help the chimney draw and the fire burn well. Nowadays we need trickle vents or mechanical fans to make the fireplace work.
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Offline SRGTD

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Re: Steaming up on "recirculate"
« Reply #5 on: 20 March 2018, 08:52 »
Recirculate doesn't let any fresh air into the car. This is needed to draw air through the car, taking moisture with it. At this time of year the car will have more moisture in it due to wet shoes and coats, so not allowing fresh air in will cause the condensation.

^This.

OP; I can understand you might want to use recirculating mode when going through tunnel to stop other cars exhaust fumes entering your car. However, if it was a choice between fumes for a few minutes and being able to see or no fumes and your vision being blocked by condensation, I’d always go for the former..
« Last Edit: 20 March 2018, 09:04 by SRGTD »
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2016 Polo GTI; Blue Silk
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Offline andyb_123

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Re: Steaming up on "recirculate"
« Reply #6 on: 20 March 2018, 13:12 »
In the Mk5, when you put recirculate on, it turns the aircon on.

The aircon system extracts moisture from the air, preventing steaming up when recirc is on. If there was no aircon, then sure, recirc would allow the moisture to build up. You see some cars steamed up like this because the owner has no idea about their air controls.

The manual explains this. We sometimes had the recirc on for 30 minutes or more (forgot to switch it off) - never had fogging issues in the Mk5.

Perhaps it'll stop being an issue when things warm up a bit, but still... An integrated aircon system shouldn't let the car steam up...

Offline mcmaddy

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Re: Steaming up on "recirculate"
« Reply #7 on: 20 March 2018, 18:28 »
Used correctly the mk7 system doesn't steam up.
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Offline andyb_123

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Re: Steaming up on "recirculate"
« Reply #8 on: 20 March 2018, 22:00 »
"Used correctly the mk7 system doesn't steam up."

What am I doing wrong then?

-Air con in "auto"
-Normal mode
-Press Recirc
-Car steams up.



Offline mcmaddy

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Re: Steaming up on "recirculate"
« Reply #9 on: 21 March 2018, 07:05 »
Get in car and press the auto button, that's it. Don't touch it ever again  :grin: seriously though in this weather at the moment your more likely to have moisture in the car so pressing recirculation button will steam the windows up. Have you had the system checked for faults? Filters changed? I haven't pressed the recirculate button on any car I've had ever. All your doing really is moving the existing air in the car which to be honest why would you do it.
TCR, Pure Grey, DCC, Dynaudio and Climate Screen.