We have a 2012 4.4TDV8 and recently the windscreen has started misting up and becoming difficult to keep clear without using the heated screen. It particularly affects the driver’s side (RH side, UK). I’m stuck. So far I’ve checked the sunroof drains and all 4 drain onto the floor freely, the sunroof shuts properly and the headlining is dry. The plenum chamber drains are clear and working. I’ve lifted the carpets and they are dry. The rear quarters and spare wheel well are dry.

The cooling system is slowly losing coolant, I top up with half a pint to a pint every couple of thousand miles. I’m suspecting a weeping heater matrix. Anything else I could have missed please? Where does the AC condensate drain to, could this also be a suspect?

Have you got the aircon on, this dehumidifies....

Set the heat to hot with aircon on, or try the dedicated front screen button which should turn it on....

You may have an airlock in the system as well, is it putting out hot air...?? Pete

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2014 L405 Autobiography SDV8 4.4 Loire Blue Ebony interior
2011 L322 Vogue SE 4.4 TDV8 Baltic Blue. Parchment over Navy Interior. Sold
2012 L322 Autobiography 5.0 Supercharged Ipanema Sand, Jet Interior. Sold
2002 L322 Vogue 4.4 V8 Epson Green, Ivory over Aspen Interior (Fatty Offroader) Sold
-Click for Project Fatty off roader-

AC on all the time, never turn it off. Even with the AC on it is struggling to stay clear, mists up when parked and takes an age to clear when setting off unless I activate the heated front screen. This is a significant departure from normal and having owned the car for nearly 6 years, it’s definitely not right now.

It is putting out hot air but it is also very slow to warm up now, I feel that’s a separate issue. Even when warm it still struggles to stay demisted.

The A/C drains under the car and usually leaves a little puddle.
Have you checked that the plenum filter is the correct way up ?.
Mike. G reg 2.5VM Vogue Portofino red 1991- 1999
V reg 2.5td P38 Rioja red 1999- 2006
53 reg td6 Vogue Oslo blue 2006- 2015
11 reg 4.4 TdV8 Vogue SE. Baltic blue 2015- date.
https://www.fullfatrr.com/forum/topic56162...tty+affair

I think it’s the correct way up, the air flows in the direction of the arrow. Interesting thought though thank you, what difference does it make to the water ingress? It looks like it is symmetrical too to bottom so I always assumed the flow was a filtration thing not a water issue.

It might be worth removing the pollen filter housing and checking the seal to the bulkhead isn’t deformed.

Water is allowed into the pollen filter housing and the drains are free flowing. Doesn’t seem designed to seal?

Is the AC working OK? Does it need serviced?

I’d be inclined to have a look under your front carpets.

It gets cold perfectly OK. It doesn’t get warm at all quickly. So I’m presuming that as it gets cold OK, the dehumidifying effect is still working as the two are inextricably linked.

nicedayforit wrote:

I’d be inclined to have a look under your front carpets.