Whirlpool Refrigerator cooling intermittently or not cooling at all

Gents,

I have older model (2005) refrigerator. It turns off after roughly 1-2 weeks and stops cooling (freezer and refrigerator. It sometimes starts when I open the door (but not every time). I tried cleaning the coils from dust etc. Tried rebooting by pushing the buttons 3 times, unplugged for 1 hour. No luck.

Is it worth to fix it? What could be causing the problem?

Thank you.