Coolant Fan Switch In The Radiator, Switching From Low To High Speed F

[309jazzpanda 41]

The fan switch located in the radiator is a 3 pin affair and i was wondering when the sensor hits a certain temp it will send a voltage out and engage the low speed fan (I think but i'm going off a modern car) Now when tis reaches a higher voltage to engage the high speed fan does it cut the voltage t the low speed?

[marksorrento205 80]

When they reach the low speed temp that powers the low speed which goes to the resistor thingy and that is what limits the speed of the fan. When it reaches the higher temp it goes direct and gives full chat.

 

Something like that

[pugdamo 111 2 Cars]

Its not the voltage that controls the speed of the cooling fan its the current.

The switch has an ignition live to it,when it gets to a certain temperature the switch will close the pin that goes through the low speed fan resistor giving you slow speed,if it continues to get hotter the switch will close the other pin in the switch that bypasses the low speed resistor giving high speed

 

Hope that answers your question

 

Damn beaten to it

Edited January 5, 2013 by pugdamo

[309jazzpanda 41]

So it will cut the power to the low speed resitor then?, I've cut my original wiring off and just have 2 fans on manual switches. I have now realised this is very stupid and i'm a stupid boy and need to rewire one of the fans up to the switch

Edited January 5, 2013 by 309jazzpanda

[marksorrento205 80]

Its not the voltage that controls the speed of the cooling fan its the current.

The switch has an ignition live to it,when it gets to a certain temperature the switch will close the pin that goes through the low speed fan resistor giving you slow speed,if it continues to get hotter the switch will close the other pin in the switch that bypasses the low speed resistor giving high speed

 

Hope that answers your question

 

Damn beaten to it

Think you did a better job

[pugdamo 111 2 Cars]

I wouldn't have thought it would have both wires out of the switch live,i would have thought it would just redirect the supply down the other wire bypassing the resistor.

If you wanted to rewire it you would need an ignition live to one of the pins then one of the wires out would need to go through the low speed resistor and the other direct to the fan.

I'm not sure of the wire numbers but if you could get hold of a wiring diagram,haynes or something then you could work out which wire goes where.M@tt on here has a PDF in his signature if you haven't got one.

[309jazzpanda 41]

Yeah got a Haynes for the wiring, I won't be using the resistor as the high speed fan I have doesn't (I hope) need one, that was the concern that it won't just shut off when it hits a higher temp though if it does I could always hit the manual switch

[pug_ham 244 3 Cars]

The switch has an ignition live to it,when it gets to a certain temperature the switch will close the pin that goes through the low speed fan resistor giving you slow speed,if it continues to get hotter the switch will close the other pin in the switch that bypasses the low speed resistor giving high speed

There is no ignition live to the cooling fans, it is a self contained loom which purely runs between the shunt box (permanent 12v), fan switch, resistor & fan.

 

Other than that it works as described, getting the fan running on the second stage can take a while, I tested the fan on TT205's old hillclimb car because he suspected he didn't have the two speed fan but it was just that he hadn't got the car hot enough for it to swap over from low speed.

 

g

[pugdamo 111 2 Cars]

I didnt do bad considering that was from memory,and mine is poor,lol

[309jazzpanda 41]

I'll just run it on low speed then use the manual to put high speed fan on

[Grim.Badger 15]

I'm not sure that's possible without a huge amount of faffing around tbh as to get the fans to run at low speed you need some kind of resistor in the curcuit.

Also, I've run my current GTi without a resistor for about 3 years now (so when it kicks in it always runs at high speed) after removing a possible faulty resistor and connecting the two wires (thick blue and thick white iirc, but I'm not 100% sure) and tbh I don't find it even remotely intrusive. I can't remember what I did with the third wire but will try and remember to check later today.

 

As G said, the loom/harness is small and self contained so it's worth taking it out (assuming it's still in there and not bypassed entirely) and checking it's condition and familiarising yourself with it. You should have connections to the: Fans, blue radiator temp switch/sensor, shunt box, resistor, and earth.

[Anthony 1,003]

If you've got two fans but no longer have the original fan wiring loom, consider just getting a relay controlled fan setup from a 205 diesel.

 

Far nicer setup than the standard 205 GTi IMO and tends to be more reliable in my experience as it's not running full current through the radiator thermoswich and the inevitably corroded unsealed connectors. The 205 diesel fan loom/relay setup is designed for twin fan setups.

[309jazzpanda 41]

Might look into that, its already got the resistor and that cut out, and I bolted the fan from my 1300 into the empty space which oddly runs at a low speed while the gti fan runs at a high speed.

It was just so I don't have to worry about manually switching but I think I can live with it

[welshpug 1,661]

I'm using a ZX wiring loom

[309jazzpanda 41]

Well thank you for that nugget of information ha ha

 

What's the difference there then?