I want to buy this electric fan 16"inch circumfrance from summit. My question is it says hook ground wire to ground and blue positive wire to 12v ignition controlled source. This is for the constant on with no relay cause i have no a/c and i dont want a thermal switch just want it on when car is on. Where do I connect for the 12v ignition controlled source? Whats the best ???
I would do the thermal switch... But if you want to do it that way, find out what size fuse the manufacturer recommends, (probably 30 for that one) and get a fuse holder. Crimp one end of that to your blue wire. Run the other end of the fuse holder to a relay. Crimp on a female spade connector and attach that wire to the pin labeled "87" on your relay. Your relay is any standard 4 or 5 pin rated for at least 30 amps (or whatever your fuse ends up being.) Using a wire no smaller than your blue wire, probably 10-12 ga, attach pin 86 on the relay to a good ground. Run pin 30 to the battery. (I use a crimp-on ring terminal and put it on the solenoid where the positive battery cable bolts up. A fuse here is a good idea too, say 20 amps) Pin 86 goes to your ignition source. Since you're using a relay and not putting the full load of that fan through your 38 year old wiring, you can put that pretty much anywhere. Tap the power wire for your radio, for instance. You could put it on the power wire going to the coil, but I think it's better to use source that cuts off while you're cranking.
That fan would only be 5" in diameter... I run a PermaCool rated at 2900 cfm with a thermal switch, I don't think I would run anything smaller as the primary means of cooling.
