Is my Alternator failing?
 

When the car is idling its reading around 14.06volts and when I put on the headlights and aircon full tilt it drops to 13.78?

I'm unsure if these figures are low or not but I've been getting some problems with my headunit and amplifier as it the volume keeps dropping or the headunit will turn off if I play music loudly. Also I'm getting an alternator whinge through my left hand speakers.:wonder:

The cars a petrol Alfa 147 btw.

Sounds more like an earthing fault to me.

check your grounds/earths for the ice and the battery in fact any you can find take them off, clean then with emery and re attach.

grand will have a go tomorrow!:thumb: