If you do not have a multimeter, unplug the refer from its 120 receptacle and plug in a hairdryer or similar. See if the hairdryer runs. If it does, then the odds are the 120 fuse on the Norcold board is blown. You have 2 fuses on the board. A 12 volt circuit fuse and the 120 heat element fuse. If the Hairdryer does not operate, then you problem is the supply 120 to the refer 120 receptacle. Either the 120 CB is tripped or the circuit is on a GFCI in the trailer and it is tripped. ALWAYS turn off all breakers and reset. DO NOT trust to just look and see if they look tripped. Doug