Electric fan relay question

Greetings,
I am installing an electric fan relay switch for the Vintage Air electric fan that’s located on the radiator. The car is a '76 XJC lumped with a 1995 LTI. The wiring calls for a blue wire to be connected to a “fused 12 volt ignition source”. This will provide power to the relay. My question, where should I look to establish this “fused ignition source”? Can I connect somewhere in the engine bay or do I need to go inside the cabin? Attached is the wiring diagram for this switch.
Thank you,
Phillip

On a Series1, the ignition relay, heater fan relay, and horn relay are possibilities. Series 2 may differ. Also, there should be power to the FI or ignition on your LTI. The relay coil draws little current, and an inline fuse is shown in your diagram (I’d make it around 3A, not 10).

BTW, with ignition-switched power, the fan will stop when the engine is switched off. If you use unswitched power (just connect pin 85 to pin 30) the fan will run until switched off by the thermostat. The inline fuse will protect the relay coil.

Robert,
Thank you for the excellent advice. I will get a chance today to put it in play.
Thanks again,
Phillip

It goes way back. But, I found fused ignition power at the passenger door post. A cylinder that looks like an old tech film container. A white wire. spliced in there. So far, many years and it performs as it should.

But, nowadays, as Bob suggests, easier sources in the engine bay abound.

Carl

Carl,

Would that be the emergency shut off for the fuel pump? That would probably be a good source though.

Thanks for the reply,

Phillip

I just completed the installation using the horn relay as the power source for the switch relay. (blue wire in diagram shown above.) It works great. Thank you so much for the sound advice. Just one quick question: the fan switch is governed by a thermostat which is installed into the lower radiator. What would be a reasonable setting, based on the temp gauge reading, to set for this fan to turn on? My gauge bounces a bit (after market) but would about 160 be a good setting?
Again, thank you for helping me with this project.
Phillip