What temperature should the fan kick in at on my Sprint. Its the original fan & there was no sign of life at 105 degrees this morning before thankfully pulling in at the MOT station.
Have you any handy tips to check whether a) the sender thing in the rad isn’t sending the signal or b) the fan is broke.
I did try a ‘search’ but only found info about people replacing theirs. Mine seemed to do the job last year so I just want to check it.
Thanks, Andrew
The fan motor has a ign supply to one side and earths out thouh the rad switch so if you earth out the wire to the switch the fan should work with the ing on . you can then join the to terminal together on the switch to check the earth to the switch.
Neil
I fitted a separate switch (under the dashboard) & warning light (in the US brake fail lamp position) as I react more quickly (nervously…) to increasing engine temperature than the radiator switch

Matthew
Thanks for that - I’ve established that the fan works but it seems to kick in at 105 degrees and keeps the temp there which seems rather high?
Thanks in anticipation
Andrew,
As you have a Sprint I assume you have the late-type, narrow water radiator with the fan controlled by an “Otter” switch that is retained in the top header tank with a rubber ring. The modern replacements for these switches are only marginally capable of handling the current drawn by the fan motor. I recommend adding a relay to the circuit to take the electrical load off of the switch. The fan in my +2 is turned on at something closer to 90C. You might put your water temperature sender into a pot of boiling water to see how accurate the gauge and sender are at 100C.
The other thing to check is the accuracy of your gauge. When reading 100 C, it may in reality only be 90 C.
Bill
To check if your fan is working; With the ignition on, unplug the otter switch and connect the two connections within the plug on the wiring harness to each other. The fan should come on. If it does not there is still hope for the fan as it may not be getting any power. Now it’s wiring/fuse checking time.