hey guys,
wanna add a fan override swith to my escort rst so i can put the cooling fan on manually if i need to.
im guessing i need some pretty heavy ish wire to the switch,but what sort of switch should i use?
i mean what sort of amps should it handle etc?
dont wanna be burning things out lol
im running twin spal fans,not sure what size they are,but the cover the whole of my full front airtec cooler.
cheers guys
steve

 

If you only want a switch there is no need for a big gauge wire,just find the earth trigger on the original relay or on the fan plug.

 

No you don't, as said above all the switch does is trip the relay, this is the very reason the system is on a relay as the switch woulden't be able to handle the power the fans draw if it were wired directly through the switch, as such it does not need heavy gauge wiring.

All you need to do is, get two pieces of standard wire gauge of desired length, place one onto the terminal that comes from the relay (It will be 12V, check with ignition ON) run this to your switch and then you run the other wire from your switch to earth, this will be an override like you want and will not effect the automated side at all.

Martin

 

(It will be 12V, check with ignition ON) run this to your switch and then you run the other wire from your switch to earth, this will be an override like you want and will not effect the automated side at all. ?????????????????????????????????????????? Are you sure !!!

 

Yes, when you close the switch you add this will bring the fans on, when open the fans will be off. The original system stays exactly as it was as we haven't touched anything, rather just piggy backed a connection off the original wiring which is what we want

Reason I say check with ignition on is I can't remember whether the fans are under ignition control or not.

Martin

 

No need for a live wire at all, just earth...

 

Your misunderstanding, I said check which side of the fan switch IS LIVE with ignition on, then run a wire from this to the switch and the other side to earth, I did not mention anywhere about live cables!

Martin

 

No problems.

 

as marty says, the fan circuit is normally permanently live on older cars so that the fan can continue to run when you switch off and walk away. if you override the temperature switch you are in danger of walking away leaving it running and flattening your battery.

why does anyone ever think they need a fan override switch???? just fit one with the proper temperature rating

 

As above the overide switch if needed shows you have cooling issues, you could put it through a changeover relay, ie one with output number 87 and 87a, then run a live to energise the relay with the ignition on, so then when you feed live to number 30(live input from battery etc) it outputs on 87 to the fan relay, then when the ignition is turned off the relay de energises, and the output flips to 87a, and hence the fans go off from the overide.
This is how mine are.
tabetha

 

Is it a good idea to fit this to a track car as will be taking constant abuse?

 

mine are on a switch on our track car

 

Some people do like to override, I don't personally, have no need, you don't want the fans on for any longer than neccessary due to the amount of power they draw, it puts alot of demand on the electrical system as a whole and can take needed power from important components such as the fuel pump.

Martin

 

not sure about that,
if i put 1 side of switch to 12v side of relay,then other side of switch to earth,surely as soon as i flick switch,ill send a earth straight to the live and trip it out.

The rts fan switch is switched live not earth.
ive put a test meter on the temp switch.
once the car temp gauge gets to half way,one of the two fan wires suddenly becomes live.
so its a switched live.
i was gonna run a manually switched live to the wire so i could throw a live feed at it as and when needed and it would still work as it should aswell.
make sense?

and does anybody know what switch i would need?
would a 25a 12v switch be ok?
cheers

 

i suggest you read up a bit more on car electrics before you set fire to something

 

how would that start a fire?
putting a live to a wire which becomes live when up to temp seems to make sense to me????
thats why im askin the question.
you could always add some input mate instead of tryin to mock me

 

like the input i made on post #9?

 

Im sure that the control relay is perm live but if you check the polarity at the fan switch it is switched earth
You just need to piggy back into the earth at the relay from your dash mounted switch standard gauge wire should be enough to cope as the switch side of the relay wont carry much load

 

Fair enough mate. Just seemed like a bit of a dig.

 

i just thought that you don't sound too sure of yourself as to what you are doing, and messing about with 25A or more can cause a fire if you get it wrong. there are some helpful hints on this thread that you should use in addition to using your internet connection to learn a bit more about it before you go ahead, as what you plan on doing does not sound like the best way to do it to me. i'm sorry if that comes across as mocking, when it's meant as advice

 

The fans are NOT switched live, the fan switch trips the relay EARTH.

The +12V you are seeing at the switch is the return from the relay (Although it should be there permanently on one side of the switch), when this is grounded this completes the relays circuit hence actuating the "Switch" part of the relay making the output terminal live and thus the fans in this case run.

Running a live to the fan switch will cause a short circuit and so it isn't wrong whats been said as it could potentially cause a fire!

As said all you need to do is run a wire from the side of the fan switch that permanently live, back to a switch and then the other side of the switch to earth when closed this will operate the fans, no lives are involved and you don't need any heavy duty wiring/switch.

It may be worth looking into the said "Uprated" fan switches as these will give better and precise operation of the fans, as you don't really want the fans on unless there needed!

Martin

 

Thanks for all your help guys. Much appreciated.
Will attempt this soon. Maybe lol.
And will keep a fire extinguisher nearby lol.

 

maybe this diagram will help as this shows a fairly normal setup (if you ignore the high speed wire). all you need to do to override the switch is connect another switch between the relay pin 86 and ground which has the same action as the temperature switch - i.e. it energises the coil of the relay to switch the high current to the fans.

any clearer?

 

OK, it is this simple you wire a switch to bypass the fan thermostat. THAT IS IT... hell I’m only an electronics graduate!

This is a 30 amp circuit on my FRST. This also means that you can only keep the fan on while the engine is on too preventing flattened battery! Also there is little benefit in keeping the fan(s) on if the engine is not running because the water pump is not moving water through the radiator to cool the engine.

 

You should not to interveen with the fans really, I don't.

It is on an automated system for a reason, as said a better way really if wanting to improve upon it is to fit a switch with a more sutiable span as they old switches are famed for there terrible spans as standard.

It's not good on the electrical system for them to be on may longer than needed as they sap mega power robbing components like the fuel pump from needed power, despite the engine being running, the charging system was not designed to provide continuous power that is needed when the fans are running for long periods of time!

Martin

 

Think I got it now cheers fellas, and thanks for the diagram , very helpfull
don't wanna run fans permanently , just want the option of having a switch there if needed.
Again, thanks for all the helpfull input.