WB Greenstar 37cdi fan runs constantly

[ajb235]

My 37cdi is in holiday mode and Eco mode, with all temp settings at minimum. However the fan ,or something, seems to be running continuously. The only way to stop this is to switch the boiler off. I do need hot water occasionally and I leave it switched on for this reason.
What is running?

 

[ShaunCorbs]

Is the blue light on or flashing ?

 

[ajb235]

Blue light is on,but not flashing.No fault codes displayed

 

[MARTIN LISTER]

Faulty fan.