Mum has been in touch saying her car (1.6 16v fabia 2) is making a screeching type noise from the aircon - It's not a constant noise but comes and goes.

 

Any ideas / obvious places I can go look next time i am visiting?  It doesn't sound like possibly leaves etc in the fan?

I had this on my Fabia one when i bought it. It just had no/little gas/oil in it. Works fine (and silently) now.