Electric Fan Wiring

I have a street rod with an electric fan on my radiator with an on/off switch mounted on the dash. I would like to wire in an Electric Fan Thermostat temperature switch that automatically comes on when the temp reaches 195 degrees and goes off at 175 degrees. The switches are available on ebay. It looks like the switch is grounded thru the engine block with the on/off at set temps internally. I want to keep the dash mounted switch so I may override the electric switch. I am not sure of how to wire it so any help would be appreciated. Thanks

you would wire the manual override on/off switch between the automatic thermostat and the fan. like this if you only want the switch to manually override to turn off... if you want an override to achieve on AND off you need to add a relayGary Sather

This is nearer to the OEM set-up, diagram A uses a simple on-off switch, B an illuminated. There is one mistake I've just realised, in B 12V+ source for the switch and 86 on the far right relay should be ignition not constant otherwise the fan could be left on permanently. fan_over_ride..png Note, this way you can over-ride at any time. The relays allow you to use thinner wires and lower current capacity switches.

You can find in ebay or aliexpress ready PCBs for this job, you need only to do the wiring job