Why does my Heater inlyworks sometimes

What is your question?

Hi so my heater only works some of the time, sometimes if I hit the side on where the radio is, it turns on, other times it turns on by itself, but most of the time it just doesn't work

What makes this problem better or worse?

It usually doesn't work at all when it's really cold out

How long has your 2009 Kia Spectra had this problem?

Since I got the car