I have an RCA side by side fridge. It runs for an 1 to 1.5 hours shuts down and starts up after 30 minutes or so with out opening the doors . There is no leaks that that I can find. Just replaced the circulation fan inside.Still runs a lot.

Your fridge may still have a very slow coolant leak that you can't detect. You may need someone to come out and check for you. Other possible causes - are you sure the light is turning off when the door is closed? 40W of heat inside could contribute. Also - make _very_ sure that the door is closing and sealing properly.