Fan won't shut off

It's designed to run continuously at a relatively low speed. Once the temps get high enough, it speeds up to enhance cooling, then slows when temps drop.

Are you also experiencing noise or have you seen fan speed with an app? At idle speed it normally is essentially silent.

I installed CapitalOne shopping yesterday. Today when I checked my battery, it said that Capital One was using significant energy and my MacBook Air seemed to be getting pretty warm. I deleted the extension (had to shut Safari and then delete Capitalne Shopping app from Applications folder. Laptop immediately cooled down.