2.0 DOHC fan switch

[cameronfurnival]

I have fitted the ford 2.0 DOHC (black top) to my Romero/ROadster but am confused over the wires for the fan. The Haynes diagram shows the fan switch is in fact two switches in one. (The colours from mine dont match the Haynes manual). My question is...do both switches come on together or is one at a higher temp, say to kick in the second fan? Or are they the same and both fans just have a separate switch? So do i need to wire in just one (as I only have one fan of course) and if so which?

If anyone knows it will be someone in this club

[keith_h]

Re: 2.0 DOHC fan switch

I have attached the pages from the Ford wiring book for the Sierra - they should help. I think the reason they used two wires was to share the current. I mounted just one of the two fans and I have put in an override switch so that I can force the fan on early if I get pulled up in a traffic jam.

Good luck

Keith

[cameronfurnival]

Re: 2.0 DOHC fan switch

Cheers Keith, your diagram has the same coloured wires as my car! I think I will follow your lead with the override idea too, better to be safe Many thanks.

[chris_cussen]

Re: 2.0 DOHC fan switch

I've got the same engine. I did write the fan up through the switch but it never seemed to kick in. So I replaced the switch with the same result. So I got an switch in a section of radiator hose pipe, you know the aluminium pipe joiner, about 42 mm diameter, with a switch in that. That never seems to kick in either. Still the hottest I have ever seen the water temp show is just under 100, but I must admitd I have been thinking about an over-ride switch too.

[cameronfurnival]

Re: 2.0 DOHC fan switch

Actually Chris, that's what prompted me to ask...running the engine till itwas hot didnt make the fan kick in at all -yet although it was obviously at working temp it didnt seem to get hotter. I think Keith's idea of emergency overide switch is a good 'un.

[keith_h]

Re: 2.0 DOHC fan switch

If you do put an override switch in don't forget to use fairly beefy wire. I can't remember if there is a plate on the fan but if there is you should be able to work out the current

[chris_cussen]

Re: 2.0 DOHC fan switch

I used the 'Premier Wiring' loom, and the rad fan wires are just about more beefy that any other wire except the alternator to battery wire. I'd guess that it must be rated at at least 10 amps

[cameronfurnival]

Re: 2.0 DOHC fan switch

I too am using that loom, must say its been a good piece of kit. I had to work out how to splice in the ecu loom but that seemed to be ok after a bit of head scratching. UNfortuanately Alan (from PWS) was dealing with a personal crisis at the time I installed it so wasnt available by phone, so everytime I wanted help I had to work it out myself - however, in retrospect it was all very easy.

[stewartdjones]

Re: 2.0 DOHC fan switch

I too have a Cabrio with the 2.0 DOHC, the engine came from a Sapphire GLSi, it had 2 fans fitted controlled from the sensor fitted to the thermostat cover, this sensor has two heat settings to control each fan seperately.
On my Cabrio I have only one fan, so I wired the sensor cables together. The heater speed control unit I fitted came from an Astra, it has incorporated within it a rear heater screen switch which I have now wired to act as an override for the fan. It works very well as before in traffic the temp did rise a bit

[Mike]

Re: 2.0 DOHC fan switch

I used the 'Premier Wiring' loom, and the rad fan wires are just about more beefy that any other wire except the alternator to battery wire. I'd guess that it must be rated at at least 10 amps

I hope the wire is rated a lot more than 10 amps - it has a 15 amp fuse in the circuit!

[chris_cussen]

Re: 2.0 DOHC fan switch

I did say is was a guess!

[Mike]

Re: 2.0 DOHC fan switch

I did say is was a guess!

Chris

I was only pulling your leg.....

I happen to be wiring in my fan at the moment, so I know what you mean about it being the thickest wire bar the alternator feed.
I have introduced a relay in to my fan circuit, along with a switched earth sender built in to the radiator, so that the rad sender only has to cope with the relay power, and not the fans power. I don't really understand electrics, as the Sierra wiring diagram in Haynes shows the fan being a switched earth direct through the sensor - so how does it cope with the current? I've also read that Sierra's had problems with the fan electrics burning out in the fuse box!
So I thought better safe than sorry!

Mike

[chris_cussen]

Re: 2.0 DOHC fan switch

I've found this on-line http://www.fordmanuals.org/page-1757.html
As you say the live feed goes to the fan, then on to the switch and finally to earth. The switch is quite substantial and should be capable of dealing with the 10amps+. You may note that there are 4 contacts on the switch. This is because there are two separate switches, which on some sierras that had two fans switched each fan indivdually.

I think I posted earlier though that my switch never seemed to kick in, and I have an alternative arrangement, that doesn't kick in either. But then the engine temperature never seems to have got above 100C

[Mike]

Re: 2.0 DOHC fan switch

I've found this on-line http://www.fordmanuals.org/page-1757.html
As you say the live feed goes to the fan, then on to the switch and finally to earth. The switch is quite substantial and should be capable of dealing with the 10amps+. You may note that there are 4 contacts on the switch. This is because there are two separate switches, which on some sierras that had two fans switched each fan indivdually.

I think I posted earlier though that my switch never seemed to kick in, and I have an alternative arrangement, that doesn't kick in either. But then the engine temperature never seems to have got above 100C

Mmmmm........ the Ford switch I have has only three terminals: one input, and two switched outputs at different temperatures. I've tested it in a boiling pan of water, so I know it works at both temperatures. It has 93.5, and 97.5 engraved in the brass collar, so I am guessing they are the temperatures at which it is supposed to kick in?
My fan is a 13" single speed Pacet, capable of shifting 2000cu. ft of air per minute, so I have wired it up with the cooler setting first, which will bring the fan in sooner. If it comes on too soon, or runs cool for long periods of time, I will cautiously test it with the higher temperature setting.
The wires to the sender are significantly smaller than those going to the fan.

Is the current less after the fan ie it is reduced by the fan? Perhaps a knowledgable electrician can answer that one?

[chris_cussen]

Re: 2.0 DOHC fan switch

Electrical current is not 'used up' as it flows, so you will need the same rating wire all the way. Like water in a pipe what goes in one end comes out the other.