April 29th, 2004 : Wiring An Electric Fan with Two Relays
After having my new Walker radiator installed with a 16-inch electric fan, I was very dissatisfied with the wiring situation. After reading about it all at MadElectrical.com, I decided to follow Mark Hamilton's advice. I ordered two relay kits, along with a bunch of other stuff, and rewired my fan. If you want to read about it, scroll down to ELECTRIC RADIATOR FAN SYSTEMS on this page.
I looked at the wiring the mechanic had originally done when he installed my new radiator and there were six things I didn't like:
1 - He ran the fan wires, which are located on the driver side of the fan, over to the passenger-side of the engine compartment and put the relay there.
2 - He ran the #86 relay wire to the ignition via my electric choke wire ... and I've got a dedicated fuse in my fuse box, from my EZ-Wire installation, just for that.
3 - He grounded the fan on a painted surface in the engine compartment.
4 - He installed a faulty circuit breaker and didn't know it.
5 - He ran a (whimpy) 14-gauge wire to my battery to power the fan with.
6 - When the fan kicked in, even after I fixed the faulty circuit breaker, my voltage gauge would drop way down and wouldn't come back up for quite a while.
Anyway, after mounting two terminal blocks on my firewall, creating a full 14.2-volt power station there (see this if you haven't already), I mounted two relays to take care of my 16-inch electric fan.
If this is your first time installing relays, the kit above is the way to go ... but once you have all the supplies and experience, you can buy Bosch relays for about $3.50 each (like I'm now doing) via Parts Express. I just phone my orders in:
1-800-338-0531 but if you'd rather, you can order from the web site:
First I disconnected my battery and mounted the two relays on the driver side in my engine compartment. Then I measured the red wires from #30 on both relays to the terminal block so I could solder them to the fusible link and make a connection to the full power there.
Next, I went under my dash and found the Electric Fan wire from my EZ-Wire kit that I had stashed away for future use ... placed a 30 amp fuse for it in the fuse box ... ran the wire out to the engine compartment and connected it to the #86 plugs on both relays.
Then I took both wires from the #85 plugs on both relays and butt-connected them to the thermostat/switch on my mainifold and then butt-connected the wires from the #87 plugs on both relays to the electric fan.
Finally, I set up a nice ground for the Ground wire on the electric fan:
Off to Mom's for dinner again, and to see how everything works. Everything worked like a charm, too! If I'm sitting at a traffic light and the fan kicks in, the needle bumps down a half-volt for a quarter-second and comes right back up. If I'm driving and the fan kicks in, the voltage gauge doesn't even react.
P.S. -- You may also be interested in checking these other electrical projects out:
Mad Electrical Improvements -- [Click Here]
Headlight Relays -- [Click Here]
Wiring Dome Light via Door Switches -- [Click Here]
Understanding Relays -- [Click Here]
About Fusible Links -- [Click Here]
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