Whining noise when I turn on heated windscreen

[hungledink78]

Hi all,

I've got a 2003 1.6 lx ford focus. I recently had to get a new windscreen which I got from my local independent garage who also fitted it, they were £100 cheaper than auto windscreens.

I've not really had cause to use the heated windscreen but when i switch it on, I notice a strange whining noise. If I have everything else on at the same time, radio, headlights, demister and wipers, engaging the heated windscreen causes the wipers to slow down and lights to dim.

Any ideas what may be the problem?

Cheers.

[mattshiz]

alternator

[anonymous-user]

Alternator is on the way out / getting old

Or slipping belt / knackered tensioner

[The Wookie]

Is the whining the auxiliary belt slipping?

The more electrical load you ask of the alternator, the more likely the belt is to slip, and the heated screen is a high demand item. Could be a knackered tensioner pulley or the alternator itself on the way out, as they are a common failure item on the 1.6

[anonymous-user]

Same issue on my Mondeo required a new alternator - it did last for about a year before it needed changing though.

[hungledink78]

Ok, thanks for the info. Will leaving the alternator have an effect on the battery, or should I get it done ASAP?

Any idea of cost and how long it takes to repair?

[davepoth]

hungledink78 said:

Ok, thanks for the info. Will leaving the alternator have an effect on the battery, or should I get it done ASAP?

Any idea of cost and how long it takes to repair?

the alternator charges the battery as well as running everything electrical on the car while the engine is on. If everything goes dim when you have lots of things on at the same time it probably means that the battery is discharging because the alternator isn't giving enough charge. In the summer it's not usually a problem - you don't have much electrical stuff in operation. But in the winter you do, and the battery has to work harder when you start the car.

Alternators are as cheap as chips for your car (a quick Google says somewhere around £30), but I have no idea how difficult it is to change one; it's not a difficult job on most everyday cars (a couple of bolts, and probably change the belt at the same time just to be certain) but access may be difficult.

[iva cosworth]

My Fiesta does this,i don't think the alternator is on the way out,it's just the extra

strain,mines only a 1.25.

HFS takes some serious volts/amps which is why it only works with engine running.

[996TT02]

Probably the alternator belt. Needs adjusting or replacing. It's straining and near-slipping. Or it may be slipping but it happens not to be so noisy. If you have any belt grip handy you could try it out just as a test.

Quite unlikely to be the alternator, if it was not producing output, it would not brake the belt... then again bearing failure is always a possibility.

[*Al*]

The missus?

[hungledink78]

Ok, thanks for the info. Will leaving the alternator have an effect on the battery, or should I get it done ASAP?

Any idea of cost and how long it takes to repair?

[996TT02]

hungledink78 said:

Ok, thanks for the info. Will leaving the alternator have an effect on the battery, or should I get it done ASAP?

Any idea of cost and how long it takes to repair?

I would just avoid using the heated screen.

Bear in mind that as soon as you start up the load on the alternator is highest as the battery has just been part drained. Many people only notice belt slip at this time. You may find that the noise goes away after a while. If not then either don't use the screen till sorted or sort it out.

If the belt needs tightening or replacing it should be obvious to any half decent mechanic and hopefully cheap to sort, they are usually placed where replacement is not difficult.