Wiring a Relay for Electric Fan

[Spectre]

Just wanted to check and see if i had this right..

Ive got an electric radiator fan off a Toyota (no idea which), and to run it simply uses 12V, and has a + and a - terminal.

I only want it to come on when The ignition is ON so a need to use a relay. Should the relay be wired like this:

85 = + coil
87 = + coil
86 = Earth
30 = + on electric fan



So is this right?

Bryce

[BradW]

Put 87 to B+ via a suitable fuse.
Are you going to have the fan on all the time when the ignition is on or are you also going to use a temp switch?

[Spectre]

for the moment im just going to have it running when the ignition is on.

What is the reason for running one of them from +B?

And how do I work out what fuse to use? 10, 15 or 20A?

[MacroP]

Almost right. You need the relay coil 85 go to ignition and 86 to earth. Technically you should have +12Volts(from the battery) on terminal 30. This should be fused before the relay too. Say a 15 Amp fuse. Terminal 87(or 87a if using the left relay) should then go to the fan.
The left relay(Single throw) is more common, so use one of those. If you happen to have the right relay(Double throw) then use terminal 87 as well(not 87a).

You do realise the fan will be on all the time when the key is on?

[Spectre]

Almost right. You need the relay coil 85 go to ignition and 86 to earth. Technically you should have +12Volts(from the battery) on terminal 30. This should be fused before the relay too. Say a 15 Amp fuse. Terminal 87(or 87a if using the left relay) should then go to the fan.
The left relay(Single throw) is more common, so use one of those. If you happen to have the right relay(Double throw) then use terminal 87 as well(not 87a).

You do realise the fan will be on all the time when the key is on?

Ignition, is this the + side of the coil?

So your saying (for the right relay, as i have one of these spare):
85: Ignition
86: earth
87: + Fan
30: + Batter (with fuse before relay)

Is it wrong to have the fan going while the car is "ON"? The only time it is on "ON" is while its running correct?

[BradW]

Wire it like this.
As MacroP said you should use 30 as your battery supply (I said 87 first up as that is what you said you were going to put to the coil).
If you can, use a circuit breaker instead of a fuse as sometimes the initial current draw when the fan first starts is enough to blow the fuse. This isn't too importanat though as you may never have a problem using a fuse (most oem systems use a fuse).

Normally single throw relays (left one in your pic) don't have an 87a, they have one or two 87 terminals.

[Spectre]

Ignition Switch, is this the + side of the coil?

[river]

Hi,

Is it wrong to have the fan going while the car is "ON"? The only time it is on "ON" is while its running correct?

No, but it is less efficient. To help the engine to get to operating temp more quickly it is best to not have the fan operating. Also, when driving at certain speeds (say 60 - 80kph) there is enough incoming air to cool the radiaotr efficiently without the need for fan assistance. At lower speeds there may not be enough air and a fan will be needed, and at high speeds the engine may generate more heat than can be effectively dissipated by the air-flow through the radiator due to road speed.

A more efficient system, with a temp switch, allows the fan to come on when the temp rises to a certain temp, and switches off when the temp goes down to a specified level.

While having the fan on all the time won't cause any great issues, it's continually pulling power and wearing itself out quicker than a switched fan would.

seeyuzz
river

[BradW]

Ignition, is this the + side of the coil?

Yes coil + is an ignition switched supply. Basically you can use anything that has power only when the ignition is on.

Is it wrong to have the fan going while the car is "ON"? The only time it is on "ON" is while its running correct?

It isn't "wrong" to have the fan on with ignition, but it is better to use a temp switch to switch it as there is no need for it to be running all the time. You can have the ignition on without the engine running,not advisable though .

Edit: What he said ^^^^^^^^^^ .

[Spectre]

Ok, so If i use a temperature switch, this is basically a relay that comes on when a "High" temp is reached?

Where does this temperature sensor sit, and where would I go to get one?
Is the pin out layouts the same as those of a relay?

[MacroP]

Ok, so If i use a temperature switch, this is basically a relay that comes on when a "High" temp is reached?

Where does this temperature sensor sit, and where would I go to get one?
Is the pin out layouts the same as those of a relay?

You use the temp switch to control the relay coil. They're not rated to turn on the fan directly. It is wired in series with the relay coil(control)) circuit.

I use the 'Tridon' switches as they are accurate, very reliable, and come in many temp ranges(ie 92 degress ON - 86 degrees OFF). Auto part retailers sell these. They are also stardard on many cars.

Do a search on here for tridon. Plenty if info here.

[sideshow]

i have these new neat all in one water temp gauge oil temp gauge
volts gauge
plus they also do programmable thermo fan controller

they look like a small turbo timer but have a temp gauge readout

there is an article in latest drift batle magazine on them
or goto my website for some details

[Spectre]

i have these new neat all in one water temp gauge oil temp gauge
volts gauge
plus they also do programmable thermo fan controller

they look like a small turbo timer but have a temp gauge readout

there is an article in latest drift batle magazine on them
or goto my website for some details

your website is....??

[Spectre]

Also, what kind of temperatures would i want for on/off for an 18RGEU? Is there somewhere on the rediator to mount the switch, and what size thread?

[Cuzzo]

http://spw.starkie.net/