It would help your cause & make things much more straightforward for those attempting to help you if you posted the MB part # found on the back of your mirror.
Dec, mine is different to that but I presume it works the same, my car has the later teardrop mirrors and the connector is moulded into the back of the mirror so it's horizontal facing rather than vertical if that makes sense?
Probably works the same way alright. Very early in the morning, if it’s well below 15°c, you should feel heat on both mirrors after about one minute, engine might need to be running.
It would help your cause & make things much more straightforward for those attempting to help you if you posted the MB part # found on the back of your mirror.
I do apologise I need to get used to how this forum works, unfortunately I don't have the part number as the glass is now back on the car. It was easy enough to get off but I found the sprung clip a bit of a PIA to get back on when refitting so I'm loathed to take it off again.