Car Window Frost Inside?

[Phil_D_UK]

My girlfriend has a S Reg Renault Megane & sometimes in the mornings the inside of her windows can be quiet wet/damp and sometime shes gets a wet patch under the carpet behind the drivers seat on the floor.

This monring the inside of her windows were frosted as we scraped all of the ice off the outside to find that the inside was frosted too, so it takes a lot longer to clear all the windows

Any idea what the problem could be?

I thought the wet patch behind the drivers seat could be a plug or something missing from underneath which in letting the water in when the roads are wet

 

[Tesla]

Water is leaking in somewhere.

I had pretty much this exact problem (but it was not cold enough to freeze) with my Ford Mondeo recently.

The other week I ended up taking the drivers seat out, lifting the carpet and all of the sound proofing/underlay was completely soaked through, I chopped it all out and it's still hung up in the garage drying off. I then had the air con on full blast for about 90minutes which dried it out a surprising amount.

I need to repeat the drying process another couple of times I reckon to get it all bone dry and then refit the underlay/sound proofing once it has dried properly.

I found the source of the leak by hosing the car down whilst all of the carpets were up. It was running down the seal between the drivers door and chassis and then in at the bottom, trickling down into the footwell which in the Mondeo is countersunk so it just filled up like a lake.

Hope this is of some help despite being a different car.

The other possibility is that your heating system is leaking (I think this will stink though?).

 

[Entai]

Aren't heater matrices a weak point on Renault's in general??

As Tesla said there would probably be a smell associated with a leaking matrix though, but damp/wet carpets is definately a sign of leaking heater, maybe have a look if she is loosing coolant.

Also a friend of mine had a Renault 19 many years ago and the pipe came off his sunroof mechanism, so the water drained down the b-pillar and into the rear footwell instead of down the drain pipe and out the rear of the car.

 

[Tesla]

Aren't heater matrices a weak point on Renault's in general??

As Tesla said there would probably be a smell associated with a leaking matrix though, but damp/wet carpets is definitely a sign of leaking heater, maybe have a look if she is loosing coolant.

Also a friend of mine had a Renault 19 many years ago and the pipe came off his sunroof mechanism, so the water drained down the b-pillar and into the rear foot well instead of down the drain pipe and out the rear of the car.

Isn't there some sort of anti-freeze in the heater matrix coolant too? If so then it probably wouldn't ice up on the window.

I am not too sure about all the above and it's just an educated guess.

 

[Phil_D_UK]

There isn't really a noticeable smell and the heaters seem to working ok, but will take all of the above into consideration

 

[Jonnycoupe]

Isn't there some sort of anti-freeze in the heater matrix coolant too? If so then it probably wouldn't ice up on the window.

I am not too sure about all the above and it's just an educated guess.

The water from the anti freeze will evaporate but not the anti freeze.

 

[Tesla]

The water from the anti freeze will evaporate but not the anti freeze.

Ah right, that makes sense. Would it stink though?

 

[Avalon]

Weak point on the S reg megy were the drain holes being blocked and rarely the ariel mount on the roof leaking. Also check the sun roof, the relay went on the other half's and wasn't shutting propperly, I swapped two motors before I eventually realised. As for drying it out best way i found was shove a dehumidifier in it for a few hours, it's quite disturbing how much water you can get out.