Hi Ger,
Where do you want to start?
It's a known issue with the 12S auxiliary connector - the high current return from the fridge is the central pin of the 7 pin plug / socket and this is also used as the locating pin / mating guide for the connector. It's very easy to damage this pin through general handling.
The connectors are un-coated brass and are prone to corrosion and high resistance causing heating
The connectors use a crude split pin design to try and make electrical contact - any corrosion or damage causes a poor contact, high resistance and heating.
Solution:
1. Replace the 12S plug and socket, once they've started to melt they are finished
2. Make sure that the plug and socket are kept clean - this applies to both the 12N and the 12S
3. Make sure that physical contact between connectors is as good as it can be.
4. Be especially careful of causing damage to the central pin
The alternative is the ISO 11446 13 pin connector - which should become a UK standard in 2008 - it's been used in Europe since 1988 - and doesn't suffer from these problems - it's waterproof and corrosion resistant, uses a twist lock to make an excellent electrical join, and is designed for currents upto 25 Amps on every connector.
Our Eriba (Hymer) Touring caravans are supplied with these 13 pin connectors - and they just work, all the time, every time.
Robert
