Rad Fans Not Running - Otter Switch?
Posted: Wed Jul 09, 2025 14:29
I'm a little concerned about the fan operation of my 1981 2.2 Elite, so thought I'd seek some 2nd opinions. Perhaps I'm worrying about nothing.
Under normal driving conditions the temp gauge floats about slightly just under 90'C. In traffic, especially during recent hot spells when it's risen past 90'C to around 95'C ish, I seem to be hearing a relay clicking near my feet around this point, but I haven't been hearing any fans kick in. Concerned for the relay, I did some diagnostic tests yesterday. A battery charger and a multi meter proved the relay to be ok on the workbench. Refitting it and shorting the otter switch connectors and then switching the ignition on sees the fans start to spin as if everything is working, so relay, fuse & fans are all good. So maybe the otter switch is playing up, but if it is, why can I hear a relay clicking? Could it be the internal contacts of the otter switch failing so not enough current will flow to operate the relay fully ? If it gets hotter will they 'make' properly and I'll hear the fans kick in? Does anybody know the nominal switching temp of the otter switch? Are there any other temperature driven switches I've overlooked?
I'm planning a (motorway) trip to the seaside on Saturday* so, with 30'C+ temperatures expected, I'd like to boost my confidence that she won't cook if the traffic log-jams.
Thanks,
James.
*Clevedon Cars & Coffee from 9:30am -12:30pm if anyone else fancies it. There'll be 200+ classic/exotic/weird/wonderful cars about the town, I thoroughly recommend it.
Under normal driving conditions the temp gauge floats about slightly just under 90'C. In traffic, especially during recent hot spells when it's risen past 90'C to around 95'C ish, I seem to be hearing a relay clicking near my feet around this point, but I haven't been hearing any fans kick in. Concerned for the relay, I did some diagnostic tests yesterday. A battery charger and a multi meter proved the relay to be ok on the workbench. Refitting it and shorting the otter switch connectors and then switching the ignition on sees the fans start to spin as if everything is working, so relay, fuse & fans are all good. So maybe the otter switch is playing up, but if it is, why can I hear a relay clicking? Could it be the internal contacts of the otter switch failing so not enough current will flow to operate the relay fully ? If it gets hotter will they 'make' properly and I'll hear the fans kick in? Does anybody know the nominal switching temp of the otter switch? Are there any other temperature driven switches I've overlooked?
I'm planning a (motorway) trip to the seaside on Saturday* so, with 30'C+ temperatures expected, I'd like to boost my confidence that she won't cook if the traffic log-jams.
Thanks,
James.
*Clevedon Cars & Coffee from 9:30am -12:30pm if anyone else fancies it. There'll be 200+ classic/exotic/weird/wonderful cars about the town, I thoroughly recommend it.