I like davewhite`s solution, one which the GoMoG webmaster utilised on his Morgans, given he covered a many miles and far from home, although well equipped, no need to get the tools out if flicking a switch could resolve the issue of a faulty otter switch and also overcome issues on later Morgans with relays incorporated in the fan control circuit, the switch by-passing both the otter and relay switching. I think Lorne may also have wired in an indicator to indicate whether the switch was in by-pass or not...?
The otter switch recently failed on my 85/6 +8 at 34k miles. There is no relay in my fans circuit, thus the otter switch takes the full current of the fan. I suspect later cars had relays fitted to take the switching current away from the otter switch. Failure in both otter switches or relays if fitted, may well be caused by the contacts in either burning, which tends to be caused when the points open switching the fan off, and which creates a spark at the points.
The spark is created by an electrical phenomena that occurs when switching off a circuit in which there are coils, such as fans and starter motors etc. I think some relays have internal diodes which can act to suppress the spark, I guess a diode could be fitted externally to achieve the same result.. ?
