how to wire an electric fan

[geeves]

How many people have wired there electric fan so it only runs when the engine runs?
I thought this a good idea until the alternator died. 400meter vertical over no more than 3km off road climb with no fan saw the temp almost in the red zone. If I had thought about it earlier I could of hooked the fan straight to the battery.

[kcsoft]

when i convert the mu over to electric fan i'm going us a 16 inch thermo and set it up to run full time when the engine is running with a switch to turn it off when it goes swimming.

I'm assuming that the fan doesn't run when the alternator is dead?? same as blower fan in the cabin?

[geeves]

Thats what happened exactly. The choice though is direct from the battery and have a thermostat control things but most thermostats wont switch 10 amps so a relay is needed. If this is from a alternator controlled feed you still loose your fan.

[Captcol]

When I had one in the capri i had a power wire from the battery going to a relay switched by the ignition then to the thermistat, then the fan. You could put the switch in the ignition line

[pig75]

I run mine through a switch so i can have them auto-off-on. The temp control output runs to the switch and a power wire then the center pin on the switch goes to the fan relay. If your temp control is negative trigger use a earth wire on the switch instead of a power wire