john g Posted July 25, 2011 Share Posted July 25, 2011 I’m wiring a radiator fan override switch to my 1600x/f. Switch and relay fitted. Should I tap the wires from the relay into the wires at the temperature sender (located in the thermostat housing) or should I tap into the wires coming from the actual radiator fan 🤔 Link to comment Share on other sites More sharing options...
Pezky Posted July 25, 2011 Share Posted July 25, 2011 When I carried out the same mod, I attached to fan temp switch. Mine was wired up so the relay effectively "short-circuited" the sender therefore switching on fan Link to comment Share on other sites More sharing options...
elie boone Posted July 25, 2011 Share Posted July 25, 2011 On the relay you have a live fused feed 30 and the 87 on the relay goes to the rad fan Link to comment Share on other sites More sharing options...
John Hughes Posted July 25, 2011 Share Posted July 25, 2011 John I did this on my old car. The wiring is complicated to explain in writing but I used the positive that originally goes to the fan switch to go to both the switched pole (pin 30) on the relay and the "coil" input (pin 85) on the relay. The output of the coil (pin 86) goes separately to a switch and also to the radiator mounted temp switch so that when either are closed they are earthed and the coil is energised. The output of the relay (pin 87) goes to the positive on the fan. If you're at MADS I can do a diagram John Link to comment Share on other sites More sharing options...
Colin Cooper Posted July 26, 2011 Share Posted July 26, 2011 Isn't it just as simple as taking a wire from each side of the temp sender to the switch. Make the switch and the fan starts through the existing relay as if the sensor had activated. Col Link to comment Share on other sites More sharing options...
CaterBram Posted July 27, 2011 Share Posted July 27, 2011 thats the way i've done it. 10a rated swich straight accross the fan temp switch using a couple of piggybag spades, works a treat Link to comment Share on other sites More sharing options...
Area Representative paul richards Posted July 27, 2011 Area Representative Share Posted July 27, 2011 Isn't it just as simple as taking a wire from each side of the temp sender to the switch. Make the switch and the fan starts through the existing relay as if the sensor had activated. Link to comment Share on other sites More sharing options...
john g Posted July 27, 2011 Author Share Posted July 27, 2011 Thanks chaps. John, no I'm not at MADS tonight. Link to comment Share on other sites More sharing options...
John Hughes Posted July 27, 2011 Share Posted July 27, 2011 See you at LADS then next week My previous car (1986 Supersprint) had no relay to start with and I didn't want to use a big high amp switch so I needed to add a relay. Link to comment Share on other sites More sharing options...
db Posted September 5, 2011 Share Posted September 5, 2011 Just wanted to make sure I've understood this correctly before I close a circuit across a component (fine if it's a switch, bad if it's the resistance). It's more of an "identifying the thing" question. My fan isn't coming on. I want to isolate the thermostat as the cause. I think the thermostat is the round device screwed with a brass fixing into the back of the top of the radiator with two wires coming out of it. If I connect those two wires directly, should:- i) the fan come on and everything be well with the world. Limp to see Mr Whiting. ii) the car blow up in an ugly electrical explosion? Thanks for your help. Link to comment Share on other sites More sharing options...
Graham Sewell Posted September 5, 2011 Share Posted September 5, 2011 If you just want to check that the thermostat switch is the problem, take a paperclip and connect the two terminals on it. The switch being the one on the filler neck. If the fan fires up with the paperclip and not with the switch (even when it is up to temperature (check the temp that tit is supposed to switch at) - then the switch is the fault. Sometimes just cleaning the terminals can help if any antifreeze has soaked the terminals at any time. Link to comment Share on other sites More sharing options...
db Posted September 5, 2011 Share Posted September 5, 2011 Thanks Graham. Imagining I'm an alien who has never seen the inside of a car ... (a good first approximation) ... is the neck of the filler where I describe the thermostat -- ie screwed into the back top of the radiator, about 1/3 from the port side, round with a brass fitting and two wires out of the back? Just short that connection? Link to comment Share on other sites More sharing options...
Graham Sewell Posted September 5, 2011 Share Posted September 5, 2011 On my (1700) xflow, just above the engine thermostat is a short column with the coolant pressure cap at the top. At the front of that column is a thermo switch for the radiator with two wires attached. I do not know the age of your 1600 xflow, but did not think that they differed that much as to have a radiator mounted switch - but I could be very wrong. Edited by - Graham Sewell on 5 Sep 2011 16:13:03 Link to comment Share on other sites More sharing options...
James_Russell Posted September 5, 2011 Share Posted September 5, 2011 I found quite a neat way of doing this mod if: -your car has no heater and -you want to use a relay instead of an additional dashboard-mounted switch Basically there is a 3-pin connector with female spade terminals which would ordinarily be where the heater fan would plug in. If you car has no heater it'll be unused and zip-tied out of the way- but it will be connected to the 3-position 'heater fan' switch on the dashboard, and will have a grey wire, a green wire and a green/yellow wire. Grey wire- Earth Green/Yellow wire- Position 1&2 live Green wire- Position 2 only live I wanted to use the redundant and conveniently marked 'fan' switch anyway so I simply ran a single, small (8A) wire to the front of the car with a male spade terminal plugged into the connector with the Green/Yellow wire. This became the switch live which would activate the relay. I earthed it with a 6" length of wire to the fixing location for the relay (I used one of the expansion bottle brackets). The connection to the fan itself was made using just 8-10" of 30A wire. I was pleased with the result- it means one very small wire to run not two thicker ones. Link to comment Share on other sites More sharing options...
db Posted September 5, 2011 Share Posted September 5, 2011 Cool. Mine's not a xflow - I've a k-series - I'm not the OP, just hijacking. The paperclip worked. I'm going to let the engine heat up and then pop the paperclip in, tape it, and drive home like that -- allowing me to limp back to safety. Presumably I'll have to rev the nuts off it to keep it warm. Excellent. Link to comment Share on other sites More sharing options...
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