[TheDufster]

Hmm, doesn't sound the same to my experience. I agree that the rear-screen seems to defrost sooner than the front but my front screen is usually all done in under two minutes with a heavy frost - completely clear.

Look really closely at the windscreen - can you see the tiny elements running from top to bottom?

I know that mine works properly because there is annoyingly one element (right in the middle) that isn't working and I get a temporary tiny stripe of frost.