Sign in to follow this  
dzincha

Rear heated window self switching on

Recommended Posts

Focus '15 made, 1.5tdci 95hp.

In cold mornings noticed that rear window is defrosting, but i didn't switched it on. 

Went to service - they said it is feature in cold weather. Wtf? If i wanted to rear window be heated i have a button for it anx i can do it. And front heating then is slow. Rear is ice free, but front is with ice.

How to deactivate this "Feature"?

 

Share this post


Link to post
Share on other sites

The rear defrost shouldn't have any effect on the front, as the car is designed to have enough power to have everything switched on at the same time. 

Share this post


Link to post
Share on other sites

But why it should be on by itself?

It makes generator more work and therefore it consumes more fuel.And sfter years battery also would be weak or dead. 

I don't get it! Why it should turn it on automatically if i have dedicated button for it?

Share this post


Link to post
Share on other sites

J is correct the car has more than enough power to defrost front and rear as well as have AC and all the other functions at the same time, have it auto switch on in the cold is a great feature at least it's one less button to press.

Share this post


Link to post
Share on other sites

1 minute ago, dzincha said:

But why it should be on by itself?

It makes generator more work and therefore it consumes more fuel.And sfter years battery also would be weak or dead. 

I don't get it! Why it should turn it on automatically if i have dedicated button for it?

Because when the weather is not freezing it can also get rid of condensation so you have a button to turn it on in such cases, it doesn't use a lot of fuel to be scared of using it, your battery will last as long as it designed to do before it needs replacing anyway. 

Share this post


Link to post
Share on other sites

It switches on both heated windows when it is below +4?

How long they are heated? Is there any way to manage them manually?

Share this post


Link to post
Share on other sites

You can't stop them coming on without pulling the fuse.

The button on the centre console if just to override them on.

No reason to turn them off, the alternator is quite capable of powering everything and still giving the battery a charge,

The charge system is much more efficient and intelligent in modern cars

Share this post


Link to post
Share on other sites

Which fuse is for rear? It is only for heated rear?

Fuse box in boot and then left department?

Share this post


Link to post
Share on other sites
3 minutes ago, dzincha said:

It switches on both heated windows when it is below +4?

How long they are heated? Is there any way to manage them manually?

My front stays on for about 10 minutes max depending on how cold it is, rear can stay on for 15 minutes then go off automatically.

Share this post


Link to post
Share on other sites

Just leave it how it is, it's not causing any problems, it's doing you a favour, smile and be happy you don't have to faff about pressing buttons.  

Share this post


Link to post
Share on other sites

I don't need super clear visibility to rear. Better to have front defrosted faster. 

In service they said if i switch button on then off - it should stop heating. 

Is it so?

Share this post


Link to post
Share on other sites

Is this "feature" also in mondeo mk5?

Share this post


Link to post
Share on other sites
Just now, dzincha said:

I don't need super clear visibility to rear. Better to have front defrosted faster. 

In service they said if i switch button on then off - it should stop heating. 

Is it so?

Possibly, but why would switching off the rear speed up the front?

It will run at around 12V regardless as the alternator has a regulator to keep the voltage consistent (for the required battery charge).

Share this post


Link to post
Share on other sites
8 minutes ago, alexp999 said:

Wouldn't surprise me if it actually helps the engine warm up quicker by increasing the load on the alternator.

It does actually, hence why I turn the heated screens and headlamps on when warming up the cars in winter.

Share this post


Link to post
Share on other sites

When in idle with ~ 900 rpm, generator is not producing a lot af amps then. If less consumers, more goes to front window.

 

 

Share this post


Link to post
Share on other sites

Revs isn't important, the smart charge system can ramp up or down electricity generation to fulfil demand.

e.g. When you accelerate it reduces load and when you take your foot off the accelerator it increases load.

The battery acts as a filter to smooth all of this out, so everything gets a constant supply.

Share this post


Link to post
Share on other sites
23 minutes ago, alexp999 said:

Revs isn't important, the smart charge system can ramp up or down electricity generation to fulfil demand.

e.g. When you accelerate it reduces load and when you take your foot off the accelerator it increases load.

The battery acts as a filter to smooth all of this out, so everything gets a constant supply.

Exactly right.  Prior to the modern-day alternator, dynamo generators were used and their rate of charge was dependant on the revs of the engine, but due to that poor design alternators became popular and completely replaced the old inefficient dynamo by the 1960s. 

If you want to test it, you can get a volt meter and check the charge going to the battery with and without the heated screens on.  I can guarantee you it will be the same regardless.

Share this post


Link to post
Share on other sites
5 hours ago, alexp999 said:

It turns the front and rear demisters on automatically at or below 4 deg C.

Perfectly normal.

Now I'm scratching my head. I've got a 2015 Tit X and mine apparently doesn't. Is this something I can turn on in Forscan?

Share this post


Link to post
Share on other sites
15 minutes ago, DJ_Andy_M said:

Now I'm scratching my head. I've got a 2015 Tit X and mine apparently doesn't. Is this something I can turn on in Forscan?

The lights won't be on. You can only tell because of the way it clears.

Share this post


Link to post
Share on other sites
10 minutes ago, alexp999 said:

The lights won't be on. You can only tell because of the way it clears.

I'll give this a test tomorrow and let the car run for 5 minutes then as I expect after todays poor attempt at snow, there will be some ice. I'm pretty convinced it isn't working though. Hello Ford warranty again if so.

Share this post


Link to post
Share on other sites
5 hours ago, dzincha said:

I don't need super clear visibility to rear. Better to have front defrosted faster. 

In service they said if i switch button on then off - it should stop heating. 

Is it so?

Turning off the rear heated windows won't defrost the front any quicker, the alternator can easily provide the full power both need at the same time.  The only way it would be quicker would be if the alternator didn't have the capacity to fully power both at the same time (which isn't the case).

Share this post


Link to post
Share on other sites

But why to heat rear window, better preheat circulation fluid to hot air blowers radiator, like vw does. 

This is veird.

Share this post


Link to post
Share on other sites
Guest
This topic is now closed to further replies.
Sign in to follow this