Real quick: what temp switch and where should temp switch be located for a dual electric fan installation? I don't want to kill my motor from overheating it. What have others done that works well?


Background:


So, I have a dual electric fan kit from V12s.com and I am very happy with the quality and construction. Before I wire it up I would like some opinions about how to turn on the fans from others who are running dual electric fans as I don't want to overheat the engine. I will be running a separate relay for each fan and 14 gauge wiring with fuses. I have read a lot about dual electric fans but there is not much information about what switch to use, what temperatures to turn the fans on and off, and where to mount the temperature switches. I currently also have a Wizard Aluminum Radiator which has a bung in the top left (USA driver side) of the radiator for a temperature switch a. I am also running 88C thermostats which is the standard USA thermostats.


Many people's auxiliary fan switch never turns on which leads me to believe the switch is set too high, on my switch it has 85C written on it but from other reading some believe it might be a 95C switch however many don't know. v12performance.com sells a replacement switch at 82C and 85C

I am currently thinking of running a dual temperature switch and wired up similar to what I have found on this website XJ-SC Modifications
I have found a switch that fits in the water pump M22x1.5 which turns on at 87C/off at 77C and 92C/82C. I am thinking of using the drivers side to turn on whenever the A/C is on and to the 92C/82C side and the passenger side to turn on with the 87C/77C side. Should I put this temperature switch in the water pump, in the radiator bung, or should I mount it in one of the inlet hoses to the radiator? Are these temperatures correct?


The only downside of this arrangement is when the A/C is on, the fan would be running nearly all the time. However this is minor as I know many factory setups that are run this way. Curious if others have done anything to fix this.


So in theory with the AC on (ie a hot day), the driver side would be on and the passenger would kick in when it needs extra cooling. If the AC is off (cooler day) the passenger would kick in when needed and if it isn't enough the driver side would kick in.



Please let me know what your thoughts are


-Scott

 

I have the same setup and just used the existing wiring after linking the 2 fans together. I didn't use any of the new supplied wiring. On the hottest day the temp gauge is always just under 90 with the standard original water pump thermo switch

 

Bottom hose sensing on teh V12 is 85c, CORECT.

That is the switch I use on ALL mine.

If the Efans rarely switch on, GOOD, the cooling system is doing what it should and is clean inside and outside. Mine rarely come on. The RH is thermo, the LH is a/c only. If the LH is on, coz the a/c is ON, the RH NEVER comes on. It is not needed, the one fan is more than ample. If the RH is ON when I switch the a/c on, obviously they both work, but the RH goes off within a minute.

88 stas are fully open (and you do not want them there), at 100c +/- 2c. Once your stats get to "full open" and stay there, they have LOST CONTROL of the cooling system, and you are in strife. Mostly 88 stats hover around the 95-97 mark.

Radiator drops coolant temp APPROX 15c from top hose to botom hose, mostly better than that, but I will stay conservative. That gives 85c APP at that switch, whish will activate it.

Mostly the bottom hose temp is at about 82-83c.

Stats are always opening and closing a small amount, so top hose sensing is unreliable. Hence Efan cars use bottom hose sensing.

Some people have gone with the Porsche, Fiat, BMW, SAAB switch in that position. These all have varying temps, and it is a personal thing. The threads on all those switches is the same as the Jag.

I have write ups on all this if you want it, but its 1am now and I am going for some much needed beauty sleep, see ya.

 

I have a new V12s.com fan kit in my XJ-S, with their 82 degree switch running the LH (aux) fan (or the A/C compressor, whichever comes on first). The RH (main) fan is on all the time. Basically, this a replication of the OEM configuration but without the mechanical bits, obviously.

It's still early days yet and I seem to have misplaced my IR thermometer but if the coolant gauge is to be believed, the car never runs quite as cool as it could with the OEM setup but is more consistent (and still at or below the middle of the N) than before. The amount of heat the fans push out from under the car certainly seems more and the "aux" fan, which could run as long as 5 minutes after shutdown before, never seems to run after shutdown for more than a minute now. In theory, the "aux" fan will kick back on when the temperature at the switch gets hot after shutdown but, as that's not where the engine gets its post-shutdown heat, it has yet to happen.

The car does seem to run cooler and easier at idle and in bumper-to-bumper traffic and not having to drive the mechanical fan does seem to make the engine feel a bit more free revving. And, maybe it's my imagination but the car seems a bit peppier as well.