Does anyone know of a good brand for aftermarket fan switches? I've been trying to find something that is adjustable so it comes on at a much lower temp. My fan works, the shop says the thermal switch works yet the fan never comes on despite the Temp gauge creeping steadily upwards in hot city traffic.

Not sure if I want to drill holes in things to add a manual toggle yet.

 

You mean the electric fan? The switches are the same as the ones used by VW, Audi and Volvo I believe, those applications have a variety of different engagement temps. I believe the stock Jag temp is 95C.

 

Vancouver, do you mean the OEM auxiliary electric fan? If so, it is controlled by the thermostatic switch in the water pump intake. This is a 22mm threaded switch and there are loads of them available with all sorts of different temp settings.
OEM I think is 85 C, so when the incoming water temp from the rad to the pump hits 85 C the fan should come on.
Changing to a (say) 80 or 82 switch is simply a matter of unscrewing the old and installing the new one. Test the circuit first by joining the two wires to the switch and making sure (ignition on, engine not!) that the fan comes on. The relay for it is under the cover in the engine bay behind the LHS headlight nacelle, and is round and red. They do fail or act up, mine did recently.
Alternatively, you can wire up the fan circuit so that it always comes on with the aircon compressor - which OEM my car did anyway. Jaguar played about with changing that from time to time.
Finally, the OEM fan is pretty poor airflow-wise. Changing it for a good aftermarket fan (eg SPAL) is a good upgrade. .

 

I bridged the wires with a copper wire it works, what do you mean by nacelle? I thought it was first in line on the bank of driver side engine bay relays? Though it may vary from car to car.

Ideally if it kicked on when the brakes are applied (ie stop lights, slow traffic) that would be ideal but I'm no electricial wizard

 

Correct it is one of those relays. The nacelle is the bulge in the bodywork that holds the light unit; on my car the relays are placed more inconveniently just aft of the nacelle under a cover.
If the circuit works, then a lower temp switch will get the fan on earlier.

 

This isn’t a bad idea. I’d want to delay the engagement until the brakes have been on for 10 seconds or so and to have it run no less than a minute. Off-on-off-on would become annoying.

 

My fans are wired 1 is on with ignition and the other is connected to the thermoswitch on the water pump inlet, my second fan does not come on until the needle is in the N.

If you want to have control of the on/off temp I would suggest a voltage switch with hysteresis like this. Can be connected to water temp sensor.

https://www.jaycar.com.au/universal-...witch/p/KC5377

 

The stock electric fan is very weak, and a lower temp switch won't stop the temp from climbing in traffic. The thermo viscous fan does most of the work, and that's what you should look at. With a new clutch, my temp stays at 1/3 with the electric fan disconnected!

 

I replaced my fan with a cheapo generic unit when it died, required a little cutting around the shroud. I straight wired it to run on the ignition and its been that way for 6 years without issue. If it dies, I'll feel like it's earned its $30 price.

 

A year or two somebody posted a link to an outfit selling just about any cooling fan switch for any car. I remember thinking that a single manufacturer probably supplies 80% of the car builders

Does anyone remember ? I searched the archives briefly; no luck

Cheers
DD

 

Vancouver
What about this:
https://www.ebay.com/itm/Derale-High...-/231850410197
or the ultimate:
http://www.dakotadigital.com/index.c...rod/prd852.htm

http://www.dakotadigital.com/pdf/PAC-2750d.pdf


Quite seriously, all these things are overkill, if you need the fan to come on a bit earlier, just get a lower temp OEM style 22mm switch!
Greg

 

Pedantic overkill is par for the course when talking about such a car!

 

I do so agree. But my experience has been that electronic controls have a half life of about 6 months, if that, in a V12 XJS. So I asked Grant, and he has a fantastic schema whereby the aux fan is on all the time with the aircon compressor, and the OEM temp switch fires the main electric fan relay; plus a manual override switch in the cabin. Works brilliantly! I used a 70 amp lorry relay for overkill and an 85 on/87 off temp switch to prevent undue cycling of the main fan relay. This was because, on my car, in stationary traffic on comes the fan; then you move on 100 yards and the water in the rad, cooled by the fan, surges through on the revs climbing as you move off; then the fan goes off, then it comes on as hot water from the engine comes back through the rad, etc etc.
Greg

 

Is there a document on this or just DIY'ed it? I've located a relay that powers on/or off a component at an RPM reading so I've emailed the company for more details. It could energize the unit then cut out the at 2000rpm and default back to the thermostatic switch afterward.

https://www.intellitronix.com/produc...tivated-switch

They make gauges to, might have to do some console rearranging.

 

Grant will sort you out. Throw a rock on his roof.
Greg

 

Damn we humans make these cars complicated.

Just got in from work, YES, bloody work, and the wife has a way better offer on the stove, so I will return with the Aussie fix.

NO rocks please, the roof paint s NEW.

 

Here ya go.

Couple of things to bear in mind, our summers are usually 45c ++, and the V12's are just fine. So, any reference to the system being below par is rubbish.

OK, probably some overkill on my part, but this was all done PRE computers and forums, so basically "suck and see" stuff.

Cooling system upgrade.doc

Thermo fan wiring drawing.pdf

The wiring is/was simple, and took all of 2 minutes to nut out.

2 relays, mini toggle switch, some wire and solder and terminals.

The FACTORY 85c thermo switch in the water pump inlet was retained to switch the earth of the RH fan.

The LH fan is A/C only.

After thought is a small toggle switch on the knee bolster, next to the dash dimmer dial, and this switch closes the earth of the RH fan relay. I use it in traffic issues IF the A/C is NOT on, just to keep the RH fan running in lieu of cycling.

BUT

If the A/C is on, so is the LH fan, and I have NEVER had the RH fan come on thermatically if the LH fan is running.

The RH fan rarely comes on if I am stooging around in our stupid 50kph speed limit suburbs, without the A/C on of course, so I know that the "overkill" I went through with the trans foam etc etc, is all now paying off very nicely, thank you very much.

On interstate runs, the temp gauge, as flaky as some are, sits a good 2 needles widths below the bottom edge of the N, no matter the ambient temp, or the speed I may be doing, usually waaaay up there.

Doing a thermo fan retro without professional cleaner/recoring of the radiator is a waste of time, in MY opinion, and YES, I still run the OE Copper/Brass radiator.

 

You could use parallel relays to control the A/C fan 1 relay switches the fan on from the A/C compressor and the other switches the fan on from the thermo switch, it does not matter if both are on at the same time as long as the polarity at the fan is the same, if it's n ot the fan will run backwards anyway.