Join Date: Mar 2002
Location: Austin, TX, USA
Re: Electirc fan help
First off, you must use a relay (not the horn relay). Trying to switch a heavy load like an electric fan on with just a switch is asking for a fire.
Personally, I'd mount my relay near the passenger's side of the core support. I'd run my power feed from the relay to the junction block on the core support behind the battery using a fusable link or a self-resetting breaker.
Connect one side of the relay coil to the power source. You can use the same power source as the load power (via breaker or fusable link), but a better approach would be to use switched accessory power to prevent the fan from running when the car is off. Connect the other side of the relay coil to a switch that grounds when activitated (temp switch, toggle switch, or both).
Ground the fans to a good ground. You can use the core support, and the block may even be better. Connect fan power to the N.O. contact of the relay.
68 Coupe, 350 w/ Edelbrock Performer RPM heads, cam, intake, 700R4, Dave's small body HEI