Need a switch to control Spal fan

[GNRick]

I need a switch with a light in it so I know when the second fan is on. I bought a lighted switch with three spade terminals- POS, ACC, Ground. The switch worked fine until I ran power to it. Then it drew major current and the wire heated up. Not what I wanted to see. However, I did get the light to come on. It was a two position toggle switch. I broke into the ground wire to one of the fans, then ran the wires to the switch. Do I need a three position switch? Thanks!

 

[novaderrik]

i assume you wired it to turn on the fan relay, and not the fan itself, correct?
the fan will draw a lot of amps, and i doubt that you bought a switch with a 50 amp rating..

since you tied into the '-' side of the fan, then you need to run the other wire to the ground, and the wire that powers the light in the switch would have to be constantly hot to light it up.

 

[GNRick]

i assume you wired it to turn on the fan relay, and not the fan itself, correct?
the fan will draw a lot of amps, and i doubt that you bought a switch with a 50 amp rating..

since you tied into the '-' side of the fan, then you need to run the other wire to the ground, and the wire that powers the light in the switch would have to be constantly hot to light it up.

It was a 30 amp switch, just wired into the negative to the fan, not to the relay. The hot wire was from the ignition fuse so it is only energized when the car is on. Did I do something wrong? Fire hazard? One wire to the switch shares the same ground as the fan that comes on all the time. Other wire from the switch completes the circuit to the fan.

 

[novaderrik]

use the switch to turn on the relay, which in turn switches on the fan.

 

[salvageV6]

Sounds like you wired up a dead short through the switch.

That type of switch can ONLY SWITCH +12 power to have the light work right and not the ground side of the fan power.

You need to wire fans with relays and to a good power source such as the alternator stud, or battery, with a fusible link or hot wire 30-50A type fuseholder rated for the inrush current, powering one fan from the IGN slot is a bit close if not over the rating for it.

If you have a switch rated for the current one fan will draw and it is a lighted three terminal switch it must switch the +12 lead, fuse the wire to the switch right off the power source such as the alternator stud or battery and run the wire to the POS side of the switch, the ACC wire will go to the
+12 connection on the fan, and wire the fan ground wire to a good ground. The ground connection on the switch only carries enough current when the switch is thrown to power the lamp or probably an led inside it. And yes wiring it this way the fan can run any time the switch is thrown but it will be wired to a source that can handle the high current.

The Best way to wire it as previously mentioned, would be with IGN power to the switch POS, ACC to the 40A rated relay coil, the other relay coil wire to a good ground, and the fan connected to one switched relay terminal and the fused alternator stud wire to the other N/O switched relay terminal. Fan ground is grounded to the battery ground or engine/ frame ground directly.

The relay can only be triggered by the switch when IGN power is present.

Use the proper terminal to make sure the fan won't run when cranking the car could be both IGN 1 and 3 or just one of them I'm not sure. Cranking may remove IGN power always anyway I don't remember and my manual isn't available right now to check. Easy to check the IGN 1 and 3 slots with a meter or test light while cranking the car with the key.

 

[GNRick]

I think I get it but I have a question- if I get power directly from the back of the alternator, would it be possible to forget that the switch is "on" when I shut the car off and if so would this just leave the led light on or would it leave the fan running or both? I would like the fan and light in the switch to shut off with the ignition or the switch- one less thing to worry about. Thanks Salvage for your time.

 

[salvageV6]

IF you wire the thing like I described USING A RELAY, when the IGN power is killed to the switch it can't activate the relay OR the light in the switch.

Kills 2 birds with one IGN key switch.

Do you know the current draw of one fan? Including inrush or turn on current required?

 

[GNRick]

IF you wire the thing like I described USING A RELAY, when the IGN power is killed to the switch it can't activate the relay OR the light in the switch.

Kills 2 birds with one IGN key switch.

Do you know the current draw of one fan? Including inrush or turn on current required?

No, but they use 30 amp fuses.

 

[drzewickid]

Spal makes a very nice fan controller for like a $100. I had one on my Mustang.. I would look into getting one of those.

 

[TurboBuRick]

IF you wire the thing like I described USING A RELAY, when the IGN power is killed to the switch it can't activate the relay OR the light in the switch.

Kills 2 birds with one IGN key switch.

Do you know the current draw of one fan? Including inrush or turn on current required?

X2 the load needs to be on the relay not switch.

Simply use a keyed power source like described by salvagev6.