I have a 2009 ford focus zetec, I haven't used the heated front windscreen in a while since its summer time but I had to go to work quite earlier the other day and had to use it as the screen had misted up. I noticed that it cleared everything but a quarter of the glass in front of the drivers side.

I know these have two fuses for each side but BOTH sides are working except for part of the drivers side. I pulled some fuses and had a look and they are fine, I've had a look at the ribbon cable behind the interior light thinking it might fix something but still nothing. I haven't taken the wipers off yet and had a look under the scuttle panel but it just seems like an odd thing. I have left it on for ages and even turned it back on when it went off on its own but that one quarter of the screen just doesn't get warm.

I've included a diagram of what I'm seeing for better understanding. Any ideas?

Probably needs a new screen.  The elements do fail eventually.

Unfortunately your windscreen heated elements have failed. As you correctly state the screen is divided in half with two fuses.

It is common as the screen gets older to loose some of the individual elements, but not so common to have a whole section fail. In the edge of the glass the elements are grouped together electrically and it would seem in your case that a common connection has broken. The only option is to replace the windscreen.  If the glass was broken then in most cases your insurance would cover it, but they don't cover the failure of the heated elements which is regarded as general wear and tear.

Not great news then. At least its not cracked and I can live with it, I'll just have to use the blowers but really not happy that it's failed. Knowing that it's broken is going to irritate me as its quite handy.

13 minutes ago, Lochlan said:

At least its not cracked

It's one of those unpredictable things, windscreens get cracked at any time so at least if yours ever does become damaged it will get replaced under the glass coverage section of of your policy.

Would there be any wires/connections other than the two on the bottom of the screen under the scuttle panel that would have something to do with the heated screen? I have recently shoved some wires up behind the roof liner at the top of the windscreen maybe and I'm not sure if I have disturbed anything. Probably just going to try a couple of things to see if it comes back to life before I accept its broken.

There is on most screens like yours only 3 connections. One each side of the screen behind the 'A' post trim and one common connection at the very top (or maybe bottom) of the screen.

If you had lost any of those 3 connections then you would not have a partly working screen.

That's a shame. Cheers for the help.

Already answered but I had this on my Mk3 Mondeo, not long after I got it. The driver half of the heated screen wasn't working and while it wasn't apparent on the test drive (i.e. it wasn't needed and would have had no visible effect other than the switch lighting up, which it did), the problem manifested itself about ten days later. I had every reason to believe the fault existed at the time of purchase.

Called Lincoln Evans Halshaw, and they said, no probs, bring it in and we'll take a look.

Champion!

So in it went, and the receptionist came back to me about an hour after, saying one of the wires was corroded and the whole screen would need replacing.

Okey dokey, when can you do it?

We're not. You'll have to go through your insurance.

EH?!!

Asked to speak to the manager and he repeated what the receptionist said.

I'm like, "you what mate? I haven't even had it two weeks! And besides, I can't claim on my insurance because it's the electrical side that's gone, it isn't cracked"

"Yes but if it *were* to develop a crack..."

"Hang on. You're refusing to fix it, and telling me to chuck a brick through my new car and commit insurance fraud?!"

The cheeky git even offered to pay the windscreen excess "out of his own pocket", like he's doing me a favour!

"Er... let me go and speak to some people"

Car booked in for a few days later, and screen replaced at home.

You'd expect that from some shady backstreet "Boycey's Autos" garage, but a nationwide chain like Evans Halshaw?

13 minutes ago, Darkman said:

You'd expect that from some shady backstreet "Boycey's Autos" garage, but a nationwide chain like Evans Halshaw?

Don't be brainwashed by big showrooms and flashy adverts.  Used car sales are the same at every level.  I was taken in by this myself!  

Agree with all the above.

But, I have a recollection that on that generation of Focus there was a known problem with the wiring to the HFS caused by the wiper mechanism.  In 2012, when I bought a 2008 Focus, one of my workmates, who had bought one earlier, stated that his HFS did not work properly, "Did Mine ?" and this was not that unusual.  It might well be worth having a look under the scuttle.

Yes there was a problem with wiper mechanism catching heated screen cables but you didn’t lose less than half the screen. You lost a whole half.  The cables go to two separate halves of screen.   If less than a whole half is missing then it can only be a problem with the metal bits encased within the glass that can’t be fixed.   On my 2007 fiesta the strips were failing when it was only about 6 years old, once bits started failing it seemed to get worse quite quickly.   Then the screen got broken and replaced.  Genuine breakage when something that looked like a bolt or a nut flew off a lorry as I was overtaking it. 

Here is an actual image of the screen for reference if anyone else is having the same issue as me: