Question

On my Thetford N150 Fridge freezer The blue light is flashing and its showing a spanner and code 1 error .I have read through all the bits and pieces that you have written and taken the lid off the power board and changed the 5amp fuse which was not blown and the 20amp which was also not blown but the blue light still flashes on the mains only. Any idees of what it might be. Thanks Gordon

Answer

Code 1 indicates that there is insufficient voltage reaching the 230 volt heater. This voltage must be between 210 and 230 volts.
The problem could be that your supply voltage is insufficient for some reason. If this is OK and the 5 amp fuse is intact then it points to a faulty AC heater or a faulty power board.