No Cooling in RS21 DABB American fridge freezer?

Fitted new Full fridge Kit and new water bottle and plugged in all worked perfectly, but after about an hour and a half the fridge and freezer start to warm up. The internal fans are both working on initial start up but after the time has lapsed it is silent and just gets warmer and warmer until I unplug and plug in again. Fault is showing as position-12 C-fan?
Any help please.