Boxster 986 frost issues

[DaveBBOXSTER]

Hi Mike F,
Yes I do have a cover that just goes over the roof section and did use it one winter and it was great (as the roof screen leaked as it was split at that time) BUT the wind blows and the cover plus ropes scratches the bodywork so it put me off ...I may do a cover with a duvet under to keep it warm! It is the cold air freezing inside that is the problem as it causes frost on the screen inside...

[DaveBBOXSTER]

Taken car out and the only thing now wrong is that the heated mirrors stay on and when driving the switch light is bright and it won't turn off at the switch...When stopped with ignition off and key out the switch light goes dim and the heating of mirrors stops. Am now thinking it could be the switch itself that is faulty? Looked behind cover but couldn't get switch out...will need to look that up.

STILL I CANNOT ACCEPT THAT the heated mirrors can still work with the fuse removed this makes no logical sense and is there a separate module or unit that controls the heated mirrors? mine is shown as 5Amp fuse \ Row C position 7 (from left?) referred to as "Terminal X" Why is it called terminal X? Seems strange that it just has a 5Amp?

Surely, if I take the heated mirror switch out or off it must stop working...If so it must be a broken switch!?!

[DaveBBOXSTER]

Removed heated screen switch but the glass stays hot. It did go off at one point during a 12 mile drive but came on again when switch was put back.
Checked CLU under seat and it seems 100% dry, clean and in good condition - picture attached.

All other bad symptoms gone except this heated mirror issue

[DaveBBOXSTER]

THANKS Mike and Particlewave,
Just went out and checked D2 30 Amp fuse it was OK and even without it in the switch was lit.

[DaveBBOXSTER]

Particlewave, just pulled the #4 block defrost relay out and NOW the switch light has finally gone out...THANKS
Does that suggest or mean it is causing the issue and is faulty and needs replacing?

If I can get a new one maybe worth trying

[DaveBBOXSTER]

Hi Mike,
Thanks for info on car cover but it is a bit outside my budget as I am out of work here in the UK. One trick I did a year ago was put a purpose made tray container of dehumidifier crystals in foot well which actually dried out the air and after a few weeks turned to water in the base but the car interior stayed dry. This simple + cheap solution did actually work just had to change the crystals, which came in a special bag to fit in the tray.

[DaveBBOXSTER]

UPDATE - Second hand £15 heater relay module 996.615.117.00 came and I fitted today. Now the heated mirror switch is finally off and goes on via the dash switch. So all now seems to be sorted. Thanks to you all for your help.