Q.Why a climbing hydrangea on a north facing wall has not ever bloomed
I’ve had this climber in my garden 5 years
No blooms ever
Lots of growth with last summers plentiful rain
Want to prune
But how and when?

Certified GKH Gardening Expert
Sometimes these are just reluctant to bloom, and have dry spells that can last several seasons or years. There are a few things you can do to help out, though. This article will help: https://www.gardeningknowhow.com/ornamental/vines/climbing-hydrangea/climbing-hydrangea-wont-bloom.htm
And Here is an article on pruning them: https://www.gardeningknowhow.com/ornamental/vines/climbing-hydrangea/climbing-hydrangea-pruning.htm