Leccy question

[jmorgan]

Been a while since I had to mess with this.

If I have 2 supplies of 12 volts to the fans, one from the water temp fan control sensor and the other from the overide switch, all the fans will see, if both happen to be on at the same time, is 12 volts? With no nasty burning smells?

[Gerry Attrick]

Assuming both switches are wired in parallel and the output of each is wired to the same terminal on the fan, all it will see is 12v.

[jmorgan]

Gerry Attrick said:

Assuming both switches are wired in parallel and the output of each is wired to the same terminal on the fan, all it will see is 12v.

Cheers. Thought so.

About to install a new fan controller but still want the overide feature. probably end up controlling the relay with the controller for the overide but want to get the engine running asap as its been sat still for 3 weeks and the overide is already wired in.

[chunder]

The water temp sensor (otter switch) will probably switch the negative of the cooling fan relay coil - the positive being wired from the ignition switch somewhere so the fan only runs with the ignition switched on.

Best way of connecting an overide switch is directly in parallel (i.e. duplicating the same two connections) with the otter switch.

Alternatively from the switch run one connection direct to the battery negative terminal and then then the other to the negative of the cooling fan relay coil. This will then allow the overide switch to bring on the fan without the ignition on - handy for cooling down at the end of a trip.

A handy tip is to also wire a 12V LED or indicator light off of the relay switched output (positive to the fan) and to the same negative terminal of the switch. This LED then acts as an indicator for when the fan is running and also proves that the relay hasn't failed.

Edited to add the usual disclaimers in case I am totally wrong !

>> Edited by chunder on Monday 9th August 15:17

[jmorgan]

Cheers Bob. Otter all sealed up now. Daft place to put it. New (refurb) rad arrived this morning. So I went for an in line (sits in th top hose) fan controller/temp sensor after seeing Patrick's at BBWF. But the old wiring to where the otter was is still there so I was going to keep that overide in place for a while. Just wanted to be sure I wasn't going to have a fire with sources of 12 volt going to the fan should bothe the overide and fan controller be on.

PS, my soddin gas iron has packed in.....so no more wiring till missis gets home to get another

>> Edited by jmorgan on Monday 9th August 15:26

[chunder]

I have an adjustable temp switch also with a capillary line in the top hose.

All you need to do is fit the two wires that went to the otter switch to the new temp switch.

[jmorgan]

Thought of that but want it to be seen to be reliable before I commit down that route. And interfering with the wiring invalidates warranty. It comes complete and wired ready to fit, relay as well. The bit of kit is a tube with a sensor the other side to the water and its potted with just the dial for temp showing.

[streaky]

With a 12v (nominal) battery, the maximum voltage is 12v (nominal), no matter how you connect the wires. It can be stepped up, but you need some electronic gubbins for that - Streaky