had17462 Posted July 26, 2018 Report Share Posted July 26, 2018 Hi all hope ur all enjoying the weather and getting the cars out. I did take the car out but it got very hot in traffic, not boiling but close . I've got an electric fan here with two wires, I am fitting a thermo switch which has 3 terminals and would like to fit a override switch just in case the thermo switch decides not to work. I remember having a extra wire fitted in the loom for a fan and have found that which is live when the ignition is on, if anyone can help I would be most grateful . Regards Nick Quote Link to post Share on other sites
Fireman049 Posted July 26, 2018 Report Share Posted July 26, 2018 Hi Nick ~ Is this of any help to you? Regards ~ Tom. Quote Link to post Share on other sites
RobH Posted July 26, 2018 Report Share Posted July 26, 2018 (edited) You may find it advantageous to use a relay to switch the fan, to save the ignition switch which otherwise will take have to carry all the fan motor current which it was not really designed to do. Relays are cheaper than new ignition switches. You can use the diagram that Tom has supplied but where the fan is connected, use the coil of a relay instead (pins 85 and 86 - it doesn't matter which way round). Take a feed from the un-switched supply with a separate in-line fuse and connect it to pin 30 on the relay. Connect the fan motor between pin 87 and earth. Make sure the fan is drawing air through the radiator in the correct direction. You haven't told us which model car this is for so its difficult to be more specific. Also if you do a forum search on the topic you should find lots of similar previous advice. Edited July 26, 2018 by RobH Quote Link to post Share on other sites
astontr6 Posted July 26, 2018 Report Share Posted July 26, 2018 You may find it advantageous to use a relay to switch the fan, to save the ignition switch which otherwise will take have to carry all the fan motor current which it was not really designed to do. Relays are cheaper than new ignition switches. You can use the diagram that Tom has supplied but where the fan is connected, use the coil of a relay instead (pins 85 and 86 - it doesn't matter which way round). Take a feed from the un-switched supply with a separate in-line fuse and connect it to pin 30 on the relay. Connect the fan motor between pin 87 and earth. Make sure the fan is drawing air through the radiator in the correct direction. You haven't told us which model car this is for so its difficult to be more specific. Also if you do a forum search on the topic you should find lots of similar previous advice. The only other point is : What size alternator do you have as an OE.15 ACR? in my view is under size to operate a Bosch type pump and an electric fan like a Kenlow as the current draw can be over 30 amps v 27 amps of a 15 ACR and this also affects the operation of the lights and indicators. My car has run a 18ACR rated at 45 amps since new and I have had no problems with slow running of my pump etc! Bruce. Bruce. Quote Link to post Share on other sites
had17462 Posted July 26, 2018 Author Report Share Posted July 26, 2018 Tom Rob Bruce thanks for the advise ,I have a temp switch in the lower metal pipe would it still be the same way. Nick Quote Link to post Share on other sites
RobH Posted July 26, 2018 Report Share Posted July 26, 2018 Now I'm confused Nick. Are you saying the pipe-fitted temperature switch has three terminals? Can you give a bit more information as to what bits you have? Was the fan system bought as a kit or are you using bits from various sources? Quote Link to post Share on other sites
Fireman049 Posted July 27, 2018 Report Share Posted July 27, 2018 Hi Nick ~ Here's how I wired my Kenlowe fan to operate with both the manual and thermo. switches. Tom. Quote Link to post Share on other sites
had17462 Posted July 27, 2018 Author Report Share Posted July 27, 2018 Tom thanks again, Rob I don't have a kit , I've got a fan with red/black wires, I have a thick brown live wire with ignition on ,from the loom , I have a lower metal water pipe with a 3 spade switch screwed in, I have a unrated alternator ,I have a toggle on off switch with two terminals. Nick Quote Link to post Share on other sites
Lebro Posted July 27, 2018 Report Share Posted July 27, 2018 Thick brown wire should be permanent live, Ignition switched is white (unfused) or green (fused) Thermo switches normally only have two terminals (on or off) Bob Quote Link to post Share on other sites
RobH Posted July 27, 2018 Report Share Posted July 27, 2018 (edited) That sounds as though your three-spade-terminal switch might be a change-over type Nick . Do you know the connection for it? Obviously you need to use the 'normally open' contacts. Tom's second diagram is right for you but it doesn't really show the +ve feeds in enough detail. If you wire it up like that with the top + connection (labelled G) fed directly from the battery via a suitable fuse and with the lower + connection( labelled R ) connected to your switched feed from the loom, the system will run automatically independent of the ignition switch but your manual override will only operate with the ignition on. (That allows the fan to run after switch-off until the water temperature has dropped. If you don't want that to happen the circuit has to be changed a bit). PS - just seen Bob's post and he is right- the thick brown wire should not be switched by the ignition. Are you sure yours is? Edited July 27, 2018 by RobH Quote Link to post Share on other sites
had17462 Posted July 27, 2018 Author Report Share Posted July 27, 2018 Ok ,I've made the fan come on with the temp sensor in the metal lower pipe but not wired in a override switch, I've made a little loom with two wires with connectors both ends from the temp sensor I've connected the brown wire to one side then the fan live to the other, then earthed the fan ,I have a spare connector on the temp switch sensor can I use that for a switch? Nick The fan comes on at 3/4 on the temp gauge. Quote Link to post Share on other sites
Lebro Posted July 27, 2018 Report Share Posted July 27, 2018 That sounds ok, but you are pulling all of the current for the fan through the thermo switch, which may not last very long. It is more usual to use the thermo switch to activate a relay, & then let the relay's heavy duty contacts supply the fan current. Re the override switch, just wire it across the same two terminals on the thermo switch that you are using already. Bob. Quote Link to post Share on other sites
had17462 Posted July 27, 2018 Author Report Share Posted July 27, 2018 Bob I need a relay between the thermo and fan? Nick Quote Link to post Share on other sites
RobH Posted July 27, 2018 Report Share Posted July 27, 2018 Nick - yes you need a relay unless you want to have to keep replacing the switch. The diagram that Tom shows in post 7 is what you want including the relay which you need. If your thick brown wire is not switched by the ignition, use that as the upper + connection in the diagram (marked as G) . If it is switched by the ignition then you will have to run a new wire as I said in post 9 or run the risk of burning out the ignition switch. Quote Link to post Share on other sites
RogerH Posted July 27, 2018 Report Share Posted July 27, 2018 Hi Nick, PM sent Roger Quote Link to post Share on other sites
had17462 Posted July 27, 2018 Author Report Share Posted July 27, 2018 Thanks guys I hate electrics Nick Quote Link to post Share on other sites
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