rad fan override switch

boucherie

New Member
Im looking for a bit of help as im sure that i read on here recently about converting the Air con on/off switch to provide a manual over ride for the cooling fans rather than put in a seperate switch.

I've had a quick search through but cant seem to find the original topic, and furthermore is anyone able to confirm which wires are which from the Air con switch to the pressure switch plug!?

Thanks and apologies if someone now goes and finds the topic straight away!
 

antgtir

New Member
I personally haven't read this thread your referencing to, however i have installed an overide switch for the rad fans. Im able to keep them running all the time whilst on track to ensure maximum cooling effect.

However i need to refine the loop as if the car is hot enough for the standard relay to work then it blows the inline fuse i installed, however if i am careful with when i start the car before an event i can keep the car cool enough to not blow the fuse (not sure if that made sense lol).

It is a good idea though to have a switch maybe similar to that of the AC or even rear demister or fog light to act as an easily accessible switch on/off point.

Would be interested myself if anyone has some form of wiring diagram they have used.

Ant.

P.s. As you probably have guessed im no electrician lol :lol:
 

Fast Guy

Moderators
Staff member
I saw what you're referring to, it mentioned about reconnecting some of the disconnected aircon wires and then the aircon switch operates the fans as normal.
 

radiobar

New Member
hi !

you can remove the aircon relay.
the switch will work fine then.
but airconsystem must be full.
on my car its actually empty and it does not work anymore.

the reason could be the pressuresensor. so it should help
to shorten it.(same when aircon is removed).
 

geoff pine

Well-Known Member
Fast Guy said:
I saw what you're referring to, it mentioned about reconnecting some of the disconnected aircon wires and then the aircon switch operates the fans as normal.
The thread was on the modifiers (look in the genaral maintinence section) sound like you join the air con pressure switch wires then use the air con switch
 
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Animaldaz

Active Member
Yep ive done this, just linked the 2 pressure sensor wires together, infact i ued a thin splitpin and taped over it to insulate. Works well but it only runs the fans at a slow speed ie not as fast as they run when they cut in normally. Im sure you could change that but i havent looked into it, but having said that i havent been ontrack to see if it works well enough as is.
 

boucherie

New Member
cheers guys, yeh ive just found it on the modifiers i think i might connect the two wires together and then see just what sort of speed the fans run at and figure out if its going to be good enough to provide constant cooling when on track
 

gtirx2

Member
I think it may of been me that posted it a while back?Just join the wires together and the fans should work just like normal when you used to put the air con on.The only down side is that the idle increases aswell like it used to,but like said above maybe if you remove the air con relay maybe the fans will still work and the idle stay the same instead of riseing?
 

gtirx2

Member
Plus i think the heater fans in the car have to be on for this to work also?I did this on the none climate control a/c heater controls,but should be the same for the climate controls.
 
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nitrosgti-r

New Member
i have a fan switch in the car as the fans have never worked for some reason? Its easy to fit. But i was advised that the fans will have no effect whilst on the track as the air flow from atmoshere when ur doin 100mph for example, the fans will almost be going backwards, ie , not having much use and making the alternater work harder, causing loss of bhp ;) Just use the switch for stationary cooling and warming up etc? AND DO NOT FORGET lol
 

boucherie

New Member
right ive had a go at sorting this out and seem to have hit a snagging point!! so can someone double check what ive done and point me in the right direction!

ive located the fan wire from the relay (brown/white) and the pressure switch wires (yellow and yellow/brown)?

ive spliced the pressure switch wires together and connected them up to the fan wire from the relay but when i start the engine the fans come on BUT the aircon switch inside the car doesnt turn them on or off and neither does the heater control. have i maybe missed something out as i will only require the fans to be on after some spirited driving and as im going round snetterton on thursday i need to sort it sharpish!

also the fans appear to run and then 'blip' out momentarily before coming back on, any ideas?!?!?

cheers
 

antgtir

New Member
Have you spliced the correct side of the relay?

I didnt bother with all this and installed a nice little toggle switch in the fuse box area for when required, works a treat with no prob's.

With regards to the on off antics, are you sure the connection is a good one? Have you soldered or just connected using plugs etc?

Ant.
 

boucherie

New Member
what ive done is connect it up about 4inches away from the fan itself so all connections are made AFTER the relay, do i need to put the connection before the relay?!

At the min ive just used connecting plugs but will solder it once i am happy its working as it should.
 

gtirx2

Member
I did not mess with the fan wires from the relay that you are on about?
All you have to do is connect the wires together that go to the a/c pressure switch [yellow/yellow and brown] then when you turn the a/c on in the car the fans should come on.But like i said before the down side to this is that the idle will rise like it used to when the air con was originaly connected up.You maybe able to stop the idle riseing by removing the a/c relay but i am not sure if the fans will still work as i have not tryed this myself yet.
The ONLY wires you need to play with for this to work are the a/c pressure switch wires yellow/yellow brown,just join them together.
 
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youngsyp

New Member
gtirx2 said:
You maybe able to stop the idle riseing by removing the a/c relay but i am not sure if the fans will still work as i have not tryed this myself yet.
Unplugging the FICD valve will stop the increase in idle speed, when the A/C switch is pressed !

Paul
 
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