Originally Posted by Aussiblue
I suspect a faulty fans speed controller.
I don't have an AU but I have a Haynes manual for an AU and the circuit diagram indicates a similar circuit to older models like my NB and NC. On these the fan speed controller sits on the firewall under the glovebox just above bottom edge od dash(small metal cast silver aluminium box) with the related main TO-3 packaged transistor sitting in the air duct to keep it cool. Water and leaves get into this duct resting against the transistor case causing it to short or fail in other ways. Pull the fan speed controller (two screws) and see if the transistor case is rusty. If so get the transistor number of the case and repost for further instructions. If it's like the old ones you can repair cheaply by buying a new Motorrolla transistor from Worldwide electronics. New fan speed controllers cost!!! Meantime pull the 40Amp air con fuse circuit breaker when you park to avoid a flat battery.
Thanks Aussiblue, I sj=hould have mentioned that I have pulled the c/b.
Will get under the dash soonest and check oput the comtroller.