Modern Macbooks have this issue, the other day I realised I had never heard the fans of it run, so I was wondering if they actually worked.

Found a web based benchmark tool that will run your CPU and GPU at 100% each. While temperatures went up to 90 degrees science... still no fans. Ended up installing a different utility to manually set the fan speed to confirm they worked.

I don't know what they did but it's good.