I have a 2007 Series III and Fuse No29 (Radio 1 & Window Switches) 5A keeps failing.

The electric windows themselves always maintain power and operate when opening and closing the doors to drop and lift a little as they do to create that perfect air-tight seal with the hood, which they're famous for!

I can continue to use the Radio by just pressing the "On" button as though I'm turning it on without the ignition so it runs for an hour and then turns itself off until I press the power button again.

The only thing therefore that does not work is the electric window switches on the doors to lower / raise the windows until I replace the fuse and then they work for a while and the fuse blows again but not always immediately, sometimes it can be a few minutes or several hundred miles of driving before not goes.

My only thought was a poor connection / semi bare wire somewhere that is shorting but how to find it!

Any brilliant and ideally simple suggestions?

5 amps is quite a low current rating for the fuse. I would tempted to try a 7.5 or 10 amp fuse assuming the intermittent fuse blowing isn't a fault as such, just the load on the motor. I would also check that window movement is not impeded.

Hi Richard, thanks for your suggestion. One reason I've not tried that is that the window motors are on a completely different Fuse so I assumed that the 5A is solely for the window switch current to turn the motor on and to power the radio.

Hi Richard, as a further thought, I guess if I tried say a 10A fuse and that also blows in the same way then at least I could be pretty sure that there is a "Short" somewhere.

Also forgot to say that I have removed both door cards and checked the visible wiring and connections behind the door cards to ensure all OK, which it was. When the fuse is fine the windows both raise and lower smoothly and at the expected pace, operating just as they should.

Yes I would agree if a 10 amp fuse blows on the window circuit then you have an issue. From your description everything seems good though so worth a try. The fuse is there to protect wiring but also to protect against overload of motor so unlikely a small increase in value will cause a problem. If you still have door cards off would he tempted to grease the mechanism if it looks like it would benefit.

BTW the radio circuit on same fuse is probably just the keep alive feed for its memory which is why you can still use radio when ignition is on as that's a different feed.

On my S2 the window cables coming from the body in the footwell through to the door are near the hinge and stay mechanism. The slot is a little too small for the number of them and they tend to pinch. This led to a couple of the wires shorting and needing to be replaced. I found this out as I asked the dealer to install some thicker speaker cable and they gave me that little look. "I don't want to be the person that says no to him!". They sorted it all in the end

Thanks Alastair. I did try to have a look when I took the door cards off, however the rubber boot between the door and car body was fitted pretty tightly and not easily removed - I'll definitely investigate further there. Being an area of movement with the door opening is a logical area of weakness over time. Cheers, Paul.

There is one other thing on the door hinge area.

The stay that holds the door (almost) in the part/full open position can wear. If you hear a "clack" or "knock" noise as it opens fully then it is wearing out. You start to feel that it is arguing as you first start to pull it closed.
There is a pin top to bottom that can wear the slot oval, then it blocks making it difficult to close the door at all.

If you start to hear the clack (drivers door gets most wear and goes first) then best to get it looked at as well. It does require some work and not just a new pin.

Also if the battery goes flat (never happens, ha ha) then the windows will often not auto dip to miss the seal as you open/close the door. There is a simple process involving the ignition in position 1 and using the window button to reset it. I say it is simple sadly I am even more simple and cannot for the life of me remember it.

I also find this useful for finding your way around some elements. https://www.aero-racing.co.uk/partsbooks/supersports/main_menu.htm
It is based on the later Aero Supersports however many aspects translate to the S3 or give you a good starting place.

Hi Alastair. Thanks again - I'll check those stays out this weekend. The window switch reset is easy - with the ignition on and doors about half open hold the window switch in the close position for 3-5 seconds whilst the windows raise fully and then lower a little - that's it. I keep mine on a C-tek at all times in the garage as with every other vehicle I own - solves a myriad of problems on cars if the battery is always tip-top. Thanks also for the link to the parts book - very useful. Cheers, Paul.