Sprint 900 Cooling Fan Manual Switch ?

Hi,
Not sure I can help, but here is what I'd do.
You need to locate the fan switch (usually on a side of the radiator). Unplug the connector, and try to "shortcut" that connector.
It will act like the fan switch reached the high temp.

Before doing that I would check a few things:
Fuses
Directly power the fan to see it the electric motor works.
Shortcut the fan switch as explained above. If the fan works, then you found the guilty. The fan switch (around 20 bucks)

 

One wire in each hole - what could possibly go wrong?!?

 

I would just insert your manual switch on the 2 poles of your fan switch (more conveniently on the 2 wires of the fan switch connector). That way the fan will work as normal, but you can also force the fan with your switch. I used that exact same principle on my old VW T25 to switch the fan on before hill climbing.
Here is a little drawing to explain.

 

Red to red
Black to black
Blue to bits

 

I would unplug the connector to check how many connectors you have on the fan switch itself.
This fan switch is usually a 2 pole contact. You'll need to find the wires that go to the poles. And you don't need to ground your switch.

There is maybe another interesting solution. It's sometime possible to find fan switch with a lower "switch on" temperature.

 

Is it okay to link to other forums?
You may find this discussion interesting.
https://www.triumphrat.net/threads/fan-temperature-switch.170450/#post-1863288

 

Really not sure why you grounded the other pole. That is for if you wanted to switch something else ie fan one way and a light the other way as you flip the button.

Im trying to figure out if this is a bad thing or a doesn’t matter thing. I’m kind of erring on doesn’t matter, other than it might confuse a future owner as they won’t know what it’s doing. Also if the switch fails it could cause some odd behaviour I.e always on if shorted from live to the second ground. Unlikely but would be a bugger to find if you forgot what you did.

 

As our friend @dilligaf used to say, them wiggly amps, work of the devil

 

I'm no auto-electrician, but I think I would check that the electric fan wiring is not still live when the ignition is turned off - otherwise you risk leaving the fan on and draining the battery. I'm pretty sure my sprint fan turns off when ignition is off, but worth a check.

 

My '96 Sprint fan runs on for a short while after the ignition is turned off. Looking at the circuit diagram in my manual, the blue/black wire on the fan thermal switch seems to go via a fuse in the fuse box to the battery positive. The blue/white wire goes to the fan.




As Aidan says, check before hard wiring a switch.