Manual Overide On Fans
Discussion
Gents,
I have just fitted a temp switch into the top hose on my 280i and would like to still have the facility of a manual overide switch on the dash. Can anyone advise how I should wire this into the fans and temp switch without blowing the fuse on the relay everytime the switch is used.
I am a bit hopeless with electrics - I am guessing I need some kind of diode that only allows power to flow on one direction but I am probably completely wrong !!!
Any advice greatly appreciated
Cheers
Ian
I have just fitted a temp switch into the top hose on my 280i and would like to still have the facility of a manual overide switch on the dash. Can anyone advise how I should wire this into the fans and temp switch without blowing the fuse on the relay everytime the switch is used.
I am a bit hopeless with electrics - I am guessing I need some kind of diode that only allows power to flow on one direction but I am probably completely wrong !!!
Any advice greatly appreciated
Cheers
Ian
So am I right in thinking I just need to fit the earth of the relay into the return feed from the overide switch and leave the live feed from the overide switch directly wired to the fan.
Let me know what you think - will it work or will it make the fuse melt when the fan kicks in !!!!
Let me know what you think - will it work or will it make the fuse melt when the fan kicks in !!!!
Don't take this the wrong way... But I've never understood why so many people are keen to fit override switches.
If it's because the fan comes on too late why not fit a lower temperature switch.
If it's because the fan comes on at the wrong time why not investigate re-locating the sensor to a more meaningful position in the coolant circuit.
If it's because you don't trust the temperature sensor(thermal snap switch) why don't you fit a more reliable one or a second one in parallel with the existing untrusted one? I'd rather place my trust in an automatic system with dual redundancy designed in rather than trust my ability to remember when to flick a switch on/off based on my best guess as to how hot things are getting six feet forward of my nose, after all I have trouble remembering to turn lights off when I go to bed and my nose or brain for that matter aren't very good at discerning temperature!
It strikes me that a backup sensor is the better solution but it doesn't provide the same degree of excitement and control as a nice big switch.
Once again I'm not having a go I just don't understand the logic.
If it's because the fan comes on too late why not fit a lower temperature switch.
If it's because the fan comes on at the wrong time why not investigate re-locating the sensor to a more meaningful position in the coolant circuit.
If it's because you don't trust the temperature sensor(thermal snap switch) why don't you fit a more reliable one or a second one in parallel with the existing untrusted one? I'd rather place my trust in an automatic system with dual redundancy designed in rather than trust my ability to remember when to flick a switch on/off based on my best guess as to how hot things are getting six feet forward of my nose, after all I have trouble remembering to turn lights off when I go to bed and my nose or brain for that matter aren't very good at discerning temperature!
It strikes me that a backup sensor is the better solution but it doesn't provide the same degree of excitement and control as a nice big switch.
Once again I'm not having a go I just don't understand the logic.
Leo,
When I got my 280 it did not have atemp switch fitted but just a manually operated switch from the dash which meant watching the temp guage in traffic and on hot days. I fitted a switch in the top coolant hose but thought as the manual switch was already wired in why not make use of it as a just in case the temp switch ever fails - hence the reason. I agree with you we should trust the technology but this is a Wedge at the end of the day !!!
Cheers
Ian
When I got my 280 it did not have atemp switch fitted but just a manually operated switch from the dash which meant watching the temp guage in traffic and on hot days. I fitted a switch in the top coolant hose but thought as the manual switch was already wired in why not make use of it as a just in case the temp switch ever fails - hence the reason. I agree with you we should trust the technology but this is a Wedge at the end of the day !!!
Cheers
Ian
Different people have their own preferences. I don't think it is necessarily a lesser solution. It's just not the way I would choose to do it. Mostly I suppose because I'm so useless at remembering to switch things off, as witnessed by the frequency the smoke detector tells me when the toast is done 
Easiest way is to have a switch that shorts out the otter switch. Run a cable with a couple of piggyback connectors down to the otter switch from the dash switch and job done. Wiring diagram is in the bible.
As for fitting one... otter switches tend to fail at the most inopportune moments and it is usually a lot easier to flick a switch and then sort things out later at home than change the switch at the road side.
As for fitting one... otter switches tend to fail at the most inopportune moments and it is usually a lot easier to flick a switch and then sort things out later at home than change the switch at the road side.
shpub said:
Easiest way is to have a switch that shorts out the otter switch. Run a cable with a couple of piggyback connectors down to the otter switch from the dash switch and job done. Wiring diagram is in the bible.
As for fitting one... otter switches tend to fail at the most inopportune moments and it is usually a lot easier to flick a switch and then sort things out later at home than change the switch at the road side.
i found this quite usefull as with the led it also gave you a visual indication of when the fan was actually running, must do it to my current wedgemobileAs for fitting one... otter switches tend to fail at the most inopportune moments and it is usually a lot easier to flick a switch and then sort things out later at home than change the switch at the road side.
Ive never had any problems with this on the wedge but did on my clio 16V..
being a large, hot running engine in a small car, it creaped up in traffic all the time and whilst most people in the club pu a manual override switch in, i just changed the thermostat cut in switch to a 5 degrees lower option and it made ALL the difference.
dad did the same on the ultima and same fix worked!
being a large, hot running engine in a small car, it creaped up in traffic all the time and whilst most people in the club pu a manual override switch in, i just changed the thermostat cut in switch to a 5 degrees lower option and it made ALL the difference.
dad did the same on the ultima and same fix worked!
Steve,
I tried your method - had a look in the bible - I have been using the existing wiring from the switch (this was already fitted by previous owner) - however what has happened now is that the fuse on the power supply to the switch blows when the manual switch (fans work on switch operation) is used and I have no auto operation of the fans from the temp switch.
I think there must be something strange on the wiring on the switch so I will fit an illuminating switch and start from scratch with the wiring - funny how a simple job never ends up that way.
Thanks for the help and advice
Cheers
Ian
I tried your method - had a look in the bible - I have been using the existing wiring from the switch (this was already fitted by previous owner) - however what has happened now is that the fuse on the power supply to the switch blows when the manual switch (fans work on switch operation) is used and I have no auto operation of the fans from the temp switch.
I think there must be something strange on the wiring on the switch so I will fit an illuminating switch and start from scratch with the wiring - funny how a simple job never ends up that way.
Thanks for the help and advice
Cheers
Ian
leorest said:
Don't take this the wrong way... But I've never understood why so many people are keen to fit override switches.
If it's because the fan comes on too late why not fit a lower temperature switch.
If it's because the fan comes on at the wrong time why not investigate re-locating the sensor to a more meaningful position in the coolant circuit.
If it's because you don't trust the temperature sensor(thermal snap switch) why don't you fit a more reliable one or a second one in parallel with the existing untrusted one? I'd rather place my trust in an automatic system with dual redundancy designed in rather than trust my ability to remember when to flick a switch on/off based on my best guess as to how hot things are getting six feet forward of my nose, after all I have trouble remembering to turn lights off when I go to bed and my nose or brain for that matter aren't very good at discerning temperature!
It strikes me that a backup sensor is the better solution but it doesn't provide the same degree of excitement and control as a nice big switch.
Once again I'm not having a go I just don't understand the logic.
Personally, it is so I can switch it on and keep it on for as long as I want. Very handy when you are anticipating a long wait in a queue of traffic on a hot day.If it's because the fan comes on too late why not fit a lower temperature switch.
If it's because the fan comes on at the wrong time why not investigate re-locating the sensor to a more meaningful position in the coolant circuit.
If it's because you don't trust the temperature sensor(thermal snap switch) why don't you fit a more reliable one or a second one in parallel with the existing untrusted one? I'd rather place my trust in an automatic system with dual redundancy designed in rather than trust my ability to remember when to flick a switch on/off based on my best guess as to how hot things are getting six feet forward of my nose, after all I have trouble remembering to turn lights off when I go to bed and my nose or brain for that matter aren't very good at discerning temperature!
It strikes me that a backup sensor is the better solution but it doesn't provide the same degree of excitement and control as a nice big switch.
Once again I'm not having a go I just don't understand the logic.
Have a Davies, Craig fan and thermostaty adjustable thingy which works great but having a switch by the steering wheel to flick on is peace of mind.
BTW - bought it as a kit - can't remember where from (think it may have been the Sheffield mob about 4 years ago) - fitting was easy and, apart from the supplied cockpit switch being rubbish, it has been great.
I find the override switch handy on trackdays as well as in long heavy traffic situations to maintain good airflow under the bonnet while slow moving or building up a lot of heat. And as mentioned before if the otter switch fails. My wedge came with it so haven't bothered with how to install one.
If fuses are blowing, there must be a short cut or something drawing a lot of amps (stereo perhaps ;-).
Rob
If fuses are blowing, there must be a short cut or something drawing a lot of amps (stereo perhaps ;-).
Rob
Sorry for the delay.
This is the Fan wiring for the 400SE using the 400SE colours.
The bit with the dotted line is what you need to add, to have a manual override.
http://www.tvr400se.co.uk/Fan-by-pass-switch.pdf
oops the 20 in the box is the fuse and fuse number.
This is the Fan wiring for the 400SE using the 400SE colours.
The bit with the dotted line is what you need to add, to have a manual override.
http://www.tvr400se.co.uk/Fan-by-pass-switch.pdf
oops the 20 in the box is the fuse and fuse number.
Edited by TVRleigh_BBWR on Thursday 10th April 15:03
Test the NU wire that go's to the fan and ground, with an ohm meter it should read a few ohms if it reading 0 then the wire to the fan is shorted to ground or the fan is broken.
this will cause the fuse to blow.
if you disconnect the fan, then you should have open curcit. this should tell you if it's the wiring or the Fan.
Not sure where your based, but if you local pop over sunday and I'll have a look.
Leigh
this will cause the fuse to blow.
if you disconnect the fan, then you should have open curcit. this should tell you if it's the wiring or the Fan.
Not sure where your based, but if you local pop over sunday and I'll have a look.
Leigh
Leigh,
looking at your circuit - the relay does not seem to have an earth attached to it - you have highlighted NC - Not Connected where I would expect to see an earth - this being the case how does the relay switch to allow power to run from the battery to NU the fan - I am not an auto electrician so please feel free to tell me I am a numpty and that it will switch.
Cheers
Ian
looking at your circuit - the relay does not seem to have an earth attached to it - you have highlighted NC - Not Connected where I would expect to see an earth - this being the case how does the relay switch to allow power to run from the battery to NU the fan - I am not an auto electrician so please feel free to tell me I am a numpty and that it will switch.
Cheers
Ian
The Relay does not need a earth.
you have two wires to the solinod that drives the main switch. to switch the fan on/off.
The relay allways has 12v feed and the sensor switches the earth, hence adding another manual switch to earth the relay, will make the relay active.
hope this makes sense.
Leigh
you have two wires to the solinod that drives the main switch. to switch the fan on/off.
The relay allways has 12v feed and the sensor switches the earth, hence adding another manual switch to earth the relay, will make the relay active.
hope this makes sense.
Leigh
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