Wiring the old/new Danfoss 25T65 thermostat

Hi,

I have an issue replacing my old Danfoss thermostat. I bought a brand new one bearing the same part number as the old one but the new one is missing a pin.

Full size image, uncropped: http://i.imgur.com/OlVSQZU.jpg

Both thermostats are referred to as “Danfoss 25T65 EN60730”. The old one (8 years) has pins 3/4/6 whereas the new one has only pins 3/4. The thermostat is plugged into an interface board (through pins 3/4/6), on which the power supply cables are connected (brown, blue, black wires). Using the original wiring of the power supply cables on the interface with the new thermostat, the fridge remains switched off.

The main electro-mechanic circuit of the old and new thermostat is shown on the last row of the image. Both have a mechanical switch (labelled “A” here) which connects pins 3 and 4. On the old one a short-circuit burnt the two contact plates. Only the old thermostat has pin 6. The latter seems to be always connected to pin 3 through a thin copper plate (labelled “B” here). This special connection obviously serves some purpose, but I cannot figure out what exactly.

The only solution I found so far is to connect permanently pins 6 and 3 using the interface board. The brown cable is now connected directly to the blue cable and to pin 3 through the interface board (cf first row of the image). This seem to work but I wonder if this solution is safe as we are dealing with high voltage circuits.

Any thoughts or advices ?