Dumb electronics question (continuity but no voltage)

Nazbit · 5 Jul 2017 at 21:16

Hi,

I think that I have a faulty relay but I don't know much about electronics so I just wanted to see if there was anything I could do or check before returning it.

My aim is to make a PC fan powered by a leisure battery switch on and off according to ambient temperature. I bought this switch from Amazon and wired it as shown below.

The switch appears to work in so far as the LCD illuminates and gives a temperature reading. When it reaches the set threshold there is a very noticeable click from the relay and the on board LED lights up to show that the relay is closed. However the fan does not spin.

The Battery is good and reads 13.10v
The Fan is good
The fan works when connected directly to the battery
The 12v and gnd terminals on the switch read 13.10 volts
When the LED on the switch is off (shows relay open), the switched terminals have no continuity
When the LED on the switch is on (shows relay closed), the switched terminals give continuity and read 00.00 voltage

So it seems to me that continuity wise the switch is working, but the terminals read no voltage at all and the fan does not spin. Does this mean that something is broken on the switch board and shorting? Or causing too higher resistance?

As you can tell I don't know what I'm talking about. I just wanted to check with someone who has a clue before I go through the hassle of returning it.

Thanks for your time

Caged · 5 Jul 2017 at 21:18

It a dry contact. You need to jumper the live from the battery into K1, the fan positive to K0, then the fan negative into GND.

Nazbit · 5 Jul 2017 at 21:34

That works. I'd never have worked that out. Thanks

Holst1981 · 5 Jul 2017 at 21:38

You have it wired up wrong.

You have powered the unit correctly

But your fan is wired up wrong.

The relay joins k0 to k1. That's all it does. There us no power fed into those terminals, just the relay joining them together.

So to make it work connect negative from the battery directly to negative on the fan.
Positive on the battery to k0 and positive on the fan to k1.