Switch it off and the light comes on

[Wasp]

I had asked for help on this topic before and thought I had it licked but, no....

I have an arming switch for my electric cooling fan, so when I want to shut it off for water crossings or so not to wear down my battery, or for sneaking up on a pack of zombies, I can do so without the fan coming on and scattering said zombies, you know how spooky they can be.....

I have a 5 pin relay running the fan, I had hoped to use the 87a pin to turn a big red light on when the arming switch was off, BUT...the 87a pin is live all the time even when the relay is off, so that idea failed.

So I'm looking for another way to turn on the red light, when the fan is disarmed, using the same disarming switch. Unfortunately my 12V electrical knowledge is that of a trout.

You're bright guys, any ideas?

J

 

[RonD]

You just have the Fan power reversed on the relay.

The power for the fan needs to be on Pin 30, you have it on pin 87(my guess), with this setup fan will still come on when relay closes, but when it opens pin 30 and pin 87a are connected, so no power on 87a, it is connected to the fan motor.

Battery---------fuse---------pin 30

pin 87----------Fan Motor------ground
pin 87a---------light-----ground

So either fan motor or light will get 12volts depending on if relay is open or closed.


I assume the on/off toggle switch for the relay(pins85/86) is fed from a Key On 12v source.

Issue you will have is that the light will stay on even when key is off since it is fed directly from the battery.

 

[RonD]

You may want to get a single throw-double pole toggle switch to use and forget the pin 87a hook up

Single throw-double pole toggle switch will have 3 connectors.
You run the 12v(key on) wire to the center pin, then relay power to either outer pin and light bulb power to the 3rd pin.
When switch is "up" power goes to relay and fan comes on, light is off
When switch is "down" power goes to light bulb and fan is off.

When key is off there is no power to the switch so light and fan are both off

 

[holyford86]

Ground side switch your fan with a relay like so, 87 to fan, 30 to ground, 87a to lamp, 85 to ground, 86 to switch, and switch to either keyed or constant power, lamp to keyed power, and finally your fan positive to constant power, with an appropriately sized fuze of course