Thread: Attention electrical guru's

put the fan on a relay

and wire the light from the back of the switch that trips the relay

Originally posted by incisor
put the fan on a relay

and wire the light from the back of the switch that trips the relay

Thanks Incisor, should the wire from the light then go to earth?

Hi Old Dog
How about one of those illuminated switches????? As far as I remember, the only extra wire neede is an earth wire for the switch.
Andrew

The pilot light should go from earth to the FAN ON side of the switch. Use a 12V LED. Draws less current, not too bright at night and more reliable.

This will essentially put the pilot light in parallel with the fan.

But as LandyAndy said, using an illuminated switch only requires an earth wire to the third terminal on the switch. [img]style_emoticons/<#EMO_DIR#>/laugh.gif[/img]

Oh, and you probably already know this, make sure the switch switches the relay, and the relay contacts switch the fan.

Buy a quality automotive relay, you can get ones that have a fuse already on them. This saves another 2 connections to give trouble down the track....

The fan will be switched by contacts 30 & 87, with 30 going to +12V and 87 to fan, and the other fan wire to earth.

The switch should go between +12V to contact 85 on the relay and 86 to earth.

The circuit is a lot easier to draw than to explain....

If you still have the circuits that came with your driving lights (if you have them!!) simply substitute the lamps for the fan! The circuit is the same, just don't wire the positive side of the relay to the high beam wire....

Okay... really dumb question why not wire the light in series rather than parrallel to the fan relay (which is the way I have always wired those sorts of things) ?

Oh and another dumb question why don't you wire the thermo fan to a three position switch (on/Off/on), auto (need a thematic switch in the engine block and switched through the ign. switch), off (for when you don't want it on at all) and manual (where fused power off the battery for when you want it on without the ign. switch being on) ??????

Hi OldDog, no matter which way you wire it up, I would recommend that you source power for the switch from your Accessories circuit so that you can have the fan running without having the motor running but you will be less likely to walk off and forget that the fan is running. They can pull a fair bit of current so it would flatten your battery in short time if you did forget.
Cheers.

Originally posted by Hellspawn
Okay... really dumb question why not wire the light in series rather than parrallel to the fan relay (which is the way I have always wired those sorts of things) ?

Oh and another dumb question why don't you wire the thermo fan to a three position switch (on/Off/on), auto (need a thematic switch in the engine block and switched through the ign. switch), off (for when you don't want it on at all) and manual (where fused power off the battery for when you want it on without the ign. switch being on) ??????

Never wire pilot lights in series with devices. You will reduce the voltage on all devices. For motors, they could burn out due to overheating.

(as an aside, a motor is an electrical device, an engine is a mechanical device. So why are there motorcycles instead of enginecycles? Natural aberation!!)

Anyway, if the pilot lamp blows, then the device in series with it will stop functioning too....

Originally posted by Moses


(as an aside, a motor is an electrical device, an engine is a mechanical device. So why are there motorcycles instead of enginecycles? Natural aberation!!)

Answer (from dictionary.com):
1. Something, such as a machine or an engine, that produces or imparts motion.
2. A device that converts any form of energy into mechanical energy, especially an internal-combustion engine or an arrangement of coils and magnets that converts electric current into mechanical power.



So not all motors are electrical. Only electrical motors are.