mine does the same i just make sure i turn the fan off when i get out, but on the plus side you running the air con regularly stops the seals degrading as for whether its a fault or not i dont know but i run mine on hot when i start most days in the winter, you should run them for 20 mins once a week
I'm not sure if the defogging logic is the same as it's been a while since I've had 1 of them, if there's nothing in your manual then a simple fix is to start up with the air direction on your feet instead of the screen.
It may seem irritating but there is logic behind it: aircon serves not one but two functions, there's the obvious one of cooling the interior in summer but there's also the less obvious function of drying the air...and that's the reason the aircon comes on with demist. Run it in recirculating modeand it'll pull all the moisture out of the interior air which is exactly whart you want it to doand demist the screen in no time
Incidentally, has anyone else noticed the typo in the MkIIhandbook? Presumeably they're referring to 'puddling' from the aircon moisture drain but Mrs Rusty's handbook says that 'pudding' may appear under the car when the aircon is running......
Apologies for dragging up an old thread but there is a solution for this 'problem', on the series II at least,and it's in the handbook- I've never noticed it before but it's a line in the aircon section.
If you don't want the aircon toautomaticallyoperate whenyou turn to demist, just turn the ignition on, set the blower control to zero and set the distribution control to screen demistonly, then you simply press the air button (the one to the right of the aircon button, opposite end to the recircbutton) 5 times within 3 seconds, the air and recirc button lights will thenflash togetherand hey presto theauto switch on function is disabled!
You now have total control over the aircon. Justfollow the same procedureagain when you want to restore automatic switch on. Edited by: mr rusty