TheBeastie Posted March 10, 2008 Share Posted March 10, 2008 I need to wire up a fan (OK got to get fan first but ..) and the instructions with the X-Fan controller have confused me. I wondered if I explained what I wanted some electrickery wizard could point me clear. I install the fan (probably ex Mondeo) and also install the X-Fan thermo switch. What I now want is the ability to switch to thermostatic control, perhaps at high and low fan speeds, or off (not sure when you would want off but everyone seems to say you need this option). Ideally I would like the fan to be low rated (for motorway) or high rated (for traffic jams or off road). I would like warning lights on the dash to show me when fan is running and also a warning red light if fan should be running but isn't. I want to control the fan through a relay (or do I need two, one for high and one for low?). I quite like the idea of the fan running on after the engine is switched off to help cool off after long run but suspect that since the water pump is not working it wont do anything! I think that covers it unless anyone can think of something I have missed. I suppose I would really like a circuit diagram showing how to wire it all up to the three tabs on the thermo switch. Also any comments or improvements on my proposed set up. Anyone got anything up their sleeves? Thanks - Malcy Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted March 10, 2008 Share Posted March 10, 2008 I have wired mine up as you say, it's a modification if Bull Bar Cowboy's circuit (which surely must be in the tech archive by now?). I have two fans and an X-Switch, and a three position (on-off-on type) switch on the dash, with a two-colour LED (green/red). With the switch in the up position, the fans run off, slow, or fast depending on temperature switch. The LED lights green for fans on slow, and red for fans on fast. With the switch in the middle position, the fans are forced off. With the switch in the down position, the fans are forced on fast. The LED lights red. I will try to remember the circuit but it's almost identical to BBC's. Quote Link to comment Share on other sites More sharing options...
GBMUD Posted March 10, 2008 Share Posted March 10, 2008 Why would you want the fans to be on at a lower temperature at different times? The water is either too hot or it is not. It is the job of the thermostat to regulate engine temperature and it is the job of the radiator to cool the coolant. The fan comes into play when the radiator is not able to cool the coolant due to a lack of air passing over it. The X-fan switch measures the temperature of water leaving the radiator and, in the event that the water leaving the radiator is above 88 degrees the lower temperature switch contacts close. If the water is leaving the radiator at 92 degrees or above then the hotter switch contacts close. All the time that the car is driving normally with the engine not labouring and cool air passing over the radiator then the fan is redundant. Only when the car is moving slowly with a load on the engine (like towing uphill) or the car is not moving and there is no air being forced over the radiator is the fan needed. This is where an electric fan is a boon, as it only runs and uses power when needed, unlike a static fan which runs all the time or a viscous fan which is better but still spins and uses engine power and therefor fuel. So, setting the fan to come on at different temperatures depending on the type of driving is not needed as there are already systems in place to maintain engine temperature in normal driving. A better use of the two switches in the X-fan switch would be to control two fans, one coming on when the 88 deg switch closes and the second at 92 deg if the first fan is still unable to reduce the temperature of the water coming out of the radiator. You could use a 2 speed fan/s in a similar way or have a single large fan running on the first, low temperature range and a red warning light/buzzer on the second switch to warn of the fact that the temperature is still high. This latter option is my own personal preference. In any case, you could easily wire a lamp to illuminate when either of the fans run - or a single one which lights different colours like FF has done. It may be possible to detect the temperature switch closing and the fan failing to start and to light a lamp but I think that would require some complicated electronics which I do not understand. Chris X-eng's helper. Quote Link to comment Share on other sites More sharing options...
TheBeastie Posted March 10, 2008 Author Share Posted March 10, 2008 Thanks for the responses. The ideas re: warning lights also good - i.e. don't bother with slow speed just with higher speed. I think the idea of the overheat light was if fan was switched off at dash accidentally, or forgotten to put back on, and engine was getting hot - perhaps not practical but sounded a good idea! As far as wiring diagram I simply got confused with the X-Eng diagram when trying to put a relay into the circuit - my electical awareness brain is very small, as Winnie The Pooh might have said! How would the relay work using two speeds on the bigger fan or is it two relays I need? Also are there likely to be two connectors on a mondeo fan ex breakers yard for the high and low settings? Sorry to be so dim! Quote Link to comment Share on other sites More sharing options...
lrfarmer Posted March 10, 2008 Share Posted March 10, 2008 I need to wire up a fan (OK got to get fan first but ..) and the instructions with the X-Fan controller have confused me. I wondered if I explained what I wanted some electrickery wizard could point me clear.I install the fan (probably ex Mondeo) and also install the X-Fan thermo switch. What I now want is the ability to switch to thermostatic control, perhaps at high and low fan speeds, or off (not sure when you would want off but everyone seems to say you need this option). Ideally I would like the fan to be low rated (for motorway) or high rated (for traffic jams or off road). I would like warning lights on the dash to show me when fan is running and also a warning red light if fan should be running but isn't. I want to control the fan through a relay (or do I need two, one for high and one for low?). I quite like the idea of the fan running on after the engine is switched off to help cool off after long run but suspect that since the water pump is not working it wont do anything! I think that covers it unless anyone can think of something I have missed. I suppose I would really like a circuit diagram showing how to wire it all up to the three tabs on the thermo switch. Also any comments or improvements on my proposed set up. Anyone got anything up their sleeves? Thanks - Malcy having an off is usfull for off roading thro water (v8's very usfull). Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted March 10, 2008 Share Posted March 10, 2008 I have an overheat warning light, the ECU controls it so it acts as a "second opinion" should the switch fail. Quote Link to comment Share on other sites More sharing options...
GBMUD Posted March 10, 2008 Share Posted March 10, 2008 As far as wiring diagram I simply got confused with the X-Eng diagram when trying to put a relay into the circuit - my electical awareness brain is very small, as Winnie The Pooh might have said! How would the relay work using two speeds on the bigger fan or is it two relays I need? Also are there likely to be two connectors on a mondeo fan ex breakers yard for the high and low settings?Sorry to be so dim! I would think that the Mondeo fan is a single speed unit so there will only be one place to connect, although I do not know this unit specifically. If you use two fans coming on separately or one 2 speed fan and you choose to (or need to) use relays then you will need one relay for each fan or each speed - i.e. low and high speed. If you need any help in interpreting the wiring diagram then give Si at X-eng a call and he will be able to help you out. He is on 01403 210124. Cheers Chris Quote Link to comment Share on other sites More sharing options...
Darren Posted March 10, 2008 Share Posted March 10, 2008 Also are there likely to be two connectors on a mondeo fan ex breakers yard for the high and low settings? The answer to that one is no. I've just bought one off of ebay and it just has two spade connectors - one for power and one for earth. If you wanted to run it as a two speed fan then you'd need to wire a big resistor in to the circuit (much like the heater fan) but I must admit that I can't see the point. It just needs to come on when the water gets too hot and go off when it's cool enough again. Quote Link to comment Share on other sites More sharing options...
TheBeastie Posted March 10, 2008 Author Share Posted March 10, 2008 OK I am slowly getting the point that keeping it simple is the clue. Assuming I find a Mondeo fan then set up as one speed fan with one relay all put through a straightforward on/off dashboard switch and aiming to come on at the low temperature setting off the thermo switch. The idea being in almost all situations the manual switch is on to allow the thermo switch to control the fan. Then wire in a warning light to come on when the manual switch is in the off position to help remind me to turn it on as soon as possible. Does that make more sense? Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted March 10, 2008 Share Posted March 10, 2008 I would wire the low temp side of the switch to turn on the fan via a relay, with a switch so you can disable it / force it on. I'd then wire the high temp side of the switch to a warning lamp so you know that: - If the fan's running and the lamp comes on, you're in trouble - If the fan's not running and it comes on, you forgot to switch the fan on or something's broken Quote Link to comment Share on other sites More sharing options...
TheBeastie Posted March 10, 2008 Author Share Posted March 10, 2008 I would wire the low temp side of the switch to turn on the fan via a relay, with a switch so you can disable it / force it on. Wouldn't that defeat the purpose of the relay in that you would have to run heavy cables all the way back to the dashboard, through the switch, and back to the fan - or am I missing something (which is more than likely!!!) Quote Link to comment Share on other sites More sharing options...
FridgeFreezer Posted March 10, 2008 Share Posted March 10, 2008 Wouldn't that defeat the purpose of the relay in that you would have to run heavy cables all the way back to the dashboard, through the switch, and back to the fan - or am I missing something (which is more than likely!!!) You put the switch in the relay coil circuit, not the heavy side Use a 3-way (on-off-on) switch, one way connects to the fan switch ("auto" mode), middle is disconnected so off, and other side goes direct to +12v to force the relay & fan on. Quote Link to comment Share on other sites More sharing options...
TheBeastie Posted March 10, 2008 Author Share Posted March 10, 2008 Ah. It is beginning to make sense now. Thanks for your patience! Best wishes Malcy Quote Link to comment Share on other sites More sharing options...
zulublue Posted March 10, 2008 Share Posted March 10, 2008 Ive had mine fitted for ages now and its never come on, even when off roading at Pay & play day's Quote Link to comment Share on other sites More sharing options...
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