had a new screen put in last week and also asked for a land rover one which insurance company approved.! but on friday morning when it was -6 a good hard frost,heated front screen had been on for about 3 mins and it was still frozen.! the bottom half had started to thaw as the heater was warming up and clearing screen.took it back to auto glass and asked,cos it was hard frost does it take longer.? they said no should be clear 30-60 secs.! they checked it today and said it was all working correct with a test they did.? waiting for it to freeze over again to check,but any ideas on this.?? cheers

30-60 seconds sounds a wee bit optimistic to me, I'm not basing my opinion on a rrs but just on other cars ive owned. If It's a hard thick frost it will take longer to thaw.

Mine took about 3-4 mins the other day with a heavy frost on it.
Don't know if that helps.  ON THE WAY: BMW F21 M140i
MERCEDES GL350 - Metallic Navy Blue w/Grey interior

GOING: BMW F31 335D MSport+ xDrive Touring
GONE: Land Rover Discovery 4 HSE - Stornaway Grey w/Black Interior (wish we'd kept it )
GONE: BMW F10 520D MSport - Carbon Black
GONE:MY12 RRS SDV6 HSE Sumatra/Ivory/Grand Black Privacy glass

thanks guy's.! yes i thought 30-60 secs was a bit quick too,so hopefully all ok