Kemerton XL 2016 fresh water tank heater blan

Hi, first time I have tried to switch the water tank frost protection heater blanket on to test it.
The blanket doesn’t appear to warm up.
The small rocker switch doesn’t show any light on it, so thinking should it? As the ambient temperature was about 8c 
is this the issue?
Can anybody help? perhaps first off do you know which fuse on the EC500 panel feeds this blanket ?

Regards Keith

Can’t help with the blanket as I’ve never used mine but it looks like it’s fuse 13. 
Edit..looking at the diagram, does the note at the bottom give any more info?

Answer to your earlier similar query in van conversion section, which is the correct section of forum for Kemerton, not Coach built.Post8ng query in multiple,e sections us not good forum etiquette and causes confusion for others when searching for answers in future
As mentioned earlier temperature has to be below 2degrees for blankets to be activated and water in both tanks. Easiest way to test is to wait until about e conditions are met, the switch on at control panel and watch increase in amps being used