RV Repair: Coach popping ground faults on the shore side, ground faults, infinite resistance

Question
I have a coach that pops ground faults breakers on the shore side.  I have diconnected the hots and neutrals and have isolated the refrig as the ground fault source.  I can remove hot, neutral, and 12 VDC and the coach is fine.  I have a Norcold Refrig.  I have also noticed that in the off position on the refrig the peizo electric starter is still firing.  Any advice? Does this direct you to a common problem? Refrig control board?

Answer
Hi Mark:
If you isolated the fridge as the source of the ground fault then the problem is either the board, the heater coil or the wires to these. If your board has a N621 board in it then it is probably the board, they are notoriously bad. My guess is that the ground fault is in the heat coil. The coil is located in a nasty environment and carries a lot of current. Disconnect the coil from the board and measure the coil resistance and also the resistance to ground. You should have 20-40 ohms coil resistance and infinite resistance to ground. My guess is that you have a partial short which is causing your ground fault.
Bill