Ford Focus ST Forum banner

1 - 16 of 16 Posts

Registered
Joined
1,053 Posts
Discussion Starter · #1 ·
Every time we get some cold weather like recently, I have this terrible misting problem, mainly on the front windscreen, but also a bit on the rear window, and despite turning on the demisters it can take ages, absolutely ages, before I can actually see where I'm going properly. It's like driving in heavy fog, with oncoming headlights giving off a blurred dazzling glow. Last night I had to crawl along for most of my journey because I could hardly see the road or anything else. The demisters? I had to keep turning the front demister on because it was more akin to a mouse farting, practically useless! I've checked by wiping the windscreen inside and out, and it doesn't seem to work either way. Most of the condensation type misting doesn't appear to be on either the inside nor the outside of the windscreen. Does anyone else have this trouble with bad misting in cold weather?
 

Registered
Joined
407 Posts
Since I see you're from England I'll give you a pass on calling the defrosters the demisters :p

Not to be dumb here, but if it's not on the inside and not on the outside, then where is it???
 
  • Like
Reactions: ddfred

Registered
Joined
180 Posts
I think the first thing to do is locate the source of the water vapor that is condensing on the windscreen. Either you have a source of water inside the car, or water vapor that you exhale is condensing on the windows. Based on your description, this last sounds improbable.

I can think of three sources of water in the car - 1) you have a leak e.g.sunroof drains or similar. Thoroughly check the carpets to see if they are wet. 2) you have a coolant leak from the heater core. Check the coolant level in the reservoir, see if it is low. Typically leaks such as this can be identified by the characteristic scent of glycol - it has a sickly sweet smell to it. Glycol is extremely poisonous, so if this is the case, please stop driving the car immediately until it is repaired. 3) water is accumulating in the heater box because the aircon drain is plugged - essentially it has become a humidifier. This seems unlikely during the winter in your climate, it more typically occurs in a warm humid environment such as the southern US.

If there is no water source in the car, perhaps your demister is not functioning properly. It should generate a very strong stream of very warm air onto the windscreen.

One last thought - are you a smoker? If yes, give the windscreen the cleaning of a lifetime, see if it helps.
 

Registered
Joined
181 Posts
For demisting/defogging the interior windows, be sure the FRESH air setting is on, not recirculate. Also, turn the AC on. This will take humidity out of the air.
 

Administrator
Joined
11,852 Posts
Check your cabin air filter, well id just replace it, its cheap

Also clean the interior and exterior of the glass throughly to eliminate variables in this troubleshoot.

I find the interior glass to get pretty dirty, creating a haze that the deforster eventually diminishes. It's weird.

So @Tomcat , new filter, clean the glass proper, and you should be sorted.
 

Registered
Joined
1,053 Posts
Discussion Starter · #6 ·
Thanks for all of these possibilities. She's going for her MOT in the next few weeks and I decided the other day to get it checked once she's there. I'll make sure to quote what you've all said to the garage. And nope, I don't smoke nor have a sunroof. Pity really about the sunroof, but UK Focus STs rarely have that nifty looking "moonroof" fitted.
 

Registered
Joined
1,053 Posts
Discussion Starter · #7 ·
Not to be dumb here, but if it's not on the inside and not on the outside, then where is it???
That's what was perplexing me. I wiped the outside, no result. Then I wiped the inside and still no result! It almost looked like the moisture was inside the glass. :confused:
 

Super Moderator
2017 Ford Fusion Sport
Joined
8,194 Posts
Check your cabin air filter, well id just replace it, its cheap

Also clean the interior and exterior of the glass throughly to eliminate variables in this troubleshoot.

I find the interior glass to get pretty dirty, creating a haze that the deforster eventually diminishes. It's weird.

So @Tomcat , new filter, clean the glass proper, and you should be sorted.
My air filter needing replaced was causing really bad haze on the INSIDE of the car...I definitely would do this just because it's cheap and easy enough. It might make a big difference.
 

Registered
Joined
407 Posts
That's what was perplexing me. I wiped the outside, no result. Then I wiped the inside and still no result! It almost looked like the moisture was inside the glass. :confused:
So just to be clear here, while it was all foggy, you wiped the inside and outside and the fog wasn't in either of those places??
That doesn't even seem possible haha. I have no clue how moisture could get on the INSIDE of the glass of the windshield. A windshield is 3 layers, 2 outer layers of tempered glass (different to the temper on the other windows) and then a PVB layer sandwiched in-between those 2 layers of glass to keep the windshield sticking together in the event of breaking and also keeping debris from only breaking the exterior layer and not coming through and breaking the interior layer.
So how moisture could get INSIDE those layers, either during manufacturing or after, I'm not sure. But I guess anything is possible haha.

Definitely tell whoever you're taking it to that it couldn't be wiped on either size if that truly is the case
 

Registered
Joined
53 Posts
My 2013 ST2 has a red button that says "Max" on the heater controls that I believe does maximum defrost. I believe it directs all the air to the defroster vents, turns the AC on (which removes humidity from the air) and turns the fan speed up. Have you tried that? If you don't have that button though, you want AC on, only defrost vents on, fan speed high, and recirculate on.

Pic of button: http://www.focusst.org/forum/attach...3-ford-focus-st-dual-zone-climate-control.jpg
 

Registered
Joined
351 Posts
I'd check to see if you have the HVAC set so that outside air comes in all the time. If you have it set on "recirc" it will fog up really bad unless the air conditioner is running.
 

Registered
Joined
407 Posts
Check out this video, this guys an engineer and did some experiments on how to defrost a window the fastest

 
  • Like
Reactions: Taz

Registered
Joined
1,053 Posts
Discussion Starter · #14 ·
I have to point out that it's like it as soon as I get in the car, at the start of the journey, not half way through the journey. I also haven't been using the heating system because the journeys are just across town, about five miles. I also wear a thick jacket so there's no reason to put the heating system on unless it gets really cold. I've noticed that the condensation type misting is worst when I get the cold warning light come on on the speedo. Ironically, lowering the driver's window a tad tends to help get rid of the condensation/misting quicker.
 

Registered
Joined
1,053 Posts
Discussion Starter · #15 ·
Check out this video, this guys an engineer and did some experiments on how to defrost a window the fastest

Ahh, you must've posted that as I was typing my last post. Veery interesting. It even verifies what I said about opening my driver's window. This guy seems like he's had the same experiences as me. For finding that vid I'd give you more than one like if I could! :)
 

Registered
Joined
407 Posts
Ahh, you must've posted that as I was typing my last post. Veery interesting. It even verifies what I said about opening my driver's window. This guy seems like he's had the same experiences as me. For finding that vid I'd give you more than one like if I could! :)
Yes lol just like cracking a window will suck smoke out of a car, it does the same with condensation.

I actually watch that guys channel regularly, this was one of the more interesting videos he has done since it's so practical!
 
1 - 16 of 16 Posts
Top