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Fan Circuit.
coozer - 17/2/07 at 09:42 PM

Anyone got a wiring diagram for a fan circuit? Obviously has to stay on after the ignition is off and I would like to put an override switch in.

Diagram, relay needed? fuse size? etc etc..

Cheers,
Steve

rusty nuts - 17/2/07 at 09:51 PM

For what they cost fit a relay, easy to fit an over ride switch to operate relay although you shopuldn't need one . Fan switches are available in loads of temperature ranges

stevec - 17/2/07 at 10:36 PM

Its not a very good sketch but I did mine like this with a 40 amp relay and a 15 amp fuse.
Fuse may be better after relay, any suggestions anyone?

[Edited on 17/2/07 by stevec]

wilkingj - 18/2/07 at 09:11 AM

quote:
Originally posted by rusty nuts
For what they cost fit a relay, easy to fit an over ride switch to operate relay although you shopuldn't need one . Fan switches are available in loads of temperature ranges



Its always best to fit a relay. The start-up current on an inductive motor shuch as a fan is very high for a split second or so.
Also if you didnt use a relay, you would want a serious switch on the dashboard that would also be able to take the full current of the Fan motor including the start up current.

Just my 2d worth

coozer - 18/2/07 at 10:36 AM

Thanks guys. I'll get cracking on that one...

wilkingj - 18/2/07 at 01:05 PM

quote:
Originally posted by stevec
Fuse may be better after relay, any suggestions anyone?
[Edited on 17/2/07 by stevec]

Always fuse the live side / feed. I would put the fuse in the feed as per your diagram.
It prevents any problem if the relay goes faulty inside and shorts out etc. I know thats a bit unlikely, but tis the principle of fusing the feeds to devices.

Also make sure the wiring can take the current. In you diagram the feed powers the relay (negligble current) and the Fan, (significant current). No problem with wiring that way, but make sure all wires are suitable for the current in that part of the circuit.

stevec - 18/2/07 at 01:52 PM

wilkingj. Thanks for the confirmation.
The fuse on mine is as the diagram and the wiring is more than man enough for the job.
The wire to pin 30 is heavy duty with a light duty bridge to pin 85. And heavy to the fan.

I just had one of those doubting moments last night when I posted the reply,
Stella Artois syndrome I think

Cheers.
Steve.

[Edited on 18/2/07 by stevec]

designer - 18/2/07 at 11:16 PM

Why bother with an override switch?

Wire the fan through a permentant supplied fuse and leave the rest to the radiator switch.

bob - 18/2/07 at 11:33 PM

Override switch

Sometimes its nice to get the fan on early in traffic during the summer months especially if using older engines which had a permanent fan running on a belt originally.