Hi Alex
As Rob saw this year a bypass can be made with a length of wire with a pair of male Lucars (spade) connectors. Use it to join th 2 otter switch wires together and bypass the Otter. For safety make one with a 10 AMP line fuse. If the fan runs with no problem it's the Otter that's faulty, if the fan does not run with no problem it's the wiring and/or fan that's suspect. If you make your test lead about 3 feet long you can cable tie it under the left hand bonnet on a convenient location and when you stop and want to turn the fan off (it will run permanently like this) just pull the fuse. Simple and convenient emergency work around. Good luck.
