In a previous post I mentioned that my auxilary fan did not work due to a seized motor drive and that I had on order an auxilary fan for my 96 XJS 2+2 convertible.

The Fan arrived!!!

I mounted the new fan to the radiator top housing cover via homemade mounting brackets. Location seems to have worked out well. The fan is 2.5" in overall width. It fit down from the top of the radiator vs the original.

I am mounting this unit to operate independent of the system...another words It will have seperate power and a switch w/ inline fuse protection so I can control as I see fit.

NOW!!!
I am going to ask some questions.

I am doing so prior to pulling things apart like seats etc which may be necessary.

My question is: Now that I have located and mounted the electric fan, where is the best spot to tie into my power and mount a seperate switch inside the cabin...preferably in a very inconspicuous location. Obviously I will also place an inline fuse...probably 15amp.

I am nervous about cutting and splicing wires under the dash unless you have something simple for me to identify.

I will need to run wires from the inside to the fan location behind the front grille.

Is it practical to run wires from the battery located in the trunk. If so, can I run underneath seats and carpet to get it into the dashboard area?

I had to do the same thing for my Merc 560SL but it was fairly simple as there was a power cable mounted on the firewall which made life easy.

I don't see anything like that on the XJS.

As always you folks are Great and I appreciate the help!!!!

Softball60 Paul

1996 Jaguar XJS 2+2 Convertible
1989 Merc 560SL
Every other British sports car known to Mankind

 

This is an interesting point to raise. First, if I may be so bold, I think your "operated only by a switch" strategy is a bit dangerous. I believe it would be better to operate the auxiliary fan in two ways:

1. Automatically from the thermostatic switch in the water pump inlet (which I think is how it is wired now), and also wire it to be on whenever the aircon is on (an easy mod).
2. Also fit a manual switch in the cabin.

This way you cannot forget to switch it on, or do so too late, and also you have manual control over it as well. I believe having the aux fan running whenever the aircon is on is a very important matter. All V12s were so wired for a time, and then they were changed for some reason.



To answer your question: Running wires through the firewall is not obvious. I believe the best way is to utilise spare unused terminals on the existing loom plug. I cannot be sure that your late model is identical to mine, but if it is, when you remove the rear wheelarch protectors on the front wheelarch, you will find a multiplug each side towards the door hinge, low down. One of these plugs will have unused terminals. On my car it was the (UK) driver's side.


These multiplugs are mirrored on the inside, down by the ankle area under the trim. You can run the trigger wire for your fan relay through to the cabin and you do not need to find a power source inside, just an earth from your switch.


Under the hood, you can take a main power source from the firewall batery posts (one each side about 2 inches down, level with the ends of the wiper grille) and run this to your relay situated somewhere up front on the radtop cross panel. The small power source for the trigger circuit for the relay can be taken off the coil positive, for example; so the circuit is turned off when you shut off the car. Then you run the trigger wire back from the relay, to the cabin switch and thence to earth.


Greg

 

If you don't want to kill the thermo operation but want to add the manual switch, it is quite simple. If you add another relay, you can even make the fan engage to the AC compressor, as Greg says.

I will upload the diagram for you afterwards.

 

wire color scheme:

G green
N brown
B black
R red
W white
U blue
S slate

If you only add manual switch, you could follow blue the additional drawing in the diagram.
If you want to add AC operation of the fan, you could use the green drawing.
You could do both, but you would want only either.

This way, you don't have to add a fuse, for you only use the existing wiring of the fan.


The wire route into the interior should be as Greg explains.

 

Softball60,

I agree with Greg's suggestion that you should also get the fan to work off the thermoswitch. However, just to politely correct Greg's suggestion - the thermoswitch on your 4 litre car is mounted near the top on the left hand tank of the radiator, not in the water pump housing.

A thought: You might want to amend your signature to indicate that you have a 4 litre car as opposed to a 6 litre v12.

Good luck with the installation

Paul

 

Thanks to all for the reply. I apologize and should have mentioned that it is a 96 XJS 4.0L.

I have another question.

Is the idea of a straight on/off direct power switch bypassing the current system concerning because of the possibility to leave on and drain the battery?....Or are there other reasons????

I had the same situation with my 560SL (overheating w/AC on, stop & go traffic during the summer heat here in Florida).

I installed the direct connect and solved the issue...didn't have any problems. I had an indicator light in line with the switch to tell me when it was on.

As always you people are GREAT!!!! and I appreciate the comments and insight.

Softball60 Paul
96XJS 4.0L 2+2 Convertible
89 Merc 560SL
Every other British Sports Car known to Mankind

 

Interesting.

I used all the original wiring to install my aftermarket fan when the OEM seized up. I just spliced new connectors at the ends, as for the cabin switch, I just cut the cables from the fan switch added enough wire, and ran those from the engine to the cabin, placing them in opposite sides of a toggle switch. That was over two years ago.

I have now become bored with having a toggle switch in the cabin. I am always paranoid about leaving it on, so I have purchased a new lower temp radiator fan switch and relay base to have the fan come on with both with the AC and the switch

 

"Is the idea of a straight on/off direct power switch bypassing the current system concerning because of the possibility to leave on and drain the battery?....Or are there other reasons????"

In my mind these are the reasons for the setup of 'auto plus manual' switching that I suggested:
First because if it comes on always with the aircon your 'merc' problem will not happen.
Second, you cannot forget to switch it on and risk overheating the engine
Third, a manual circuit is a good backup if the auto circuit fails (though this is a more important consideration with the v12).

Greg

 

I am very skiddish about these electrical things. Want to keep it as simple for me to understand as possible.

The plug ( 2pin) that fit into the original fan mating connector has no resistance, which, I hope, tells me that there is no current. The temp sensor on the thermostat seems to be working. Don't know if this means the relay is no good???

You see where I am going....I figured that a switch is the best solution considering that "if the system did work the fan wouldn't go on until the temp reaches ~200 F".

That scares me!!!!

I wanted more control, but am afraid to start cutting and splicing into the original circuit.

Even the simple ones like suggessted in previous responses.

I probably need a shot of courage!!!! to do it the correct way!!!!


Thanks

Softball60 Paul
96 XJS 4.0L 2+2 convertible
89Merc 560SL
Every other British Sportscar known to Mankind

 

Paul,

I'm not sure what you mean by the "The temp sensor on the thermostat..". The auxiliary fan is driven off a thermoswitch mounted in the radiator not the temp sensor in the thermostat housing. The thermoswitch is on the left hand side of teh raditor tank, about 2/3rds of the way up. It's described in the Parts & Service Manual and visible in the Parts diagram.

My apols if that's what you already understood.

Paul

 

You can check the resistance even there is no current on the circuit.
You have to check the voltage or amperage if you want to know whether the circuit is on.
If the fan isn't working there is no current, that is not so complicated.




My scheme is based on Greg's post, and when you use that you can force the fan to run if the original circuit fails. And if you control the fan only manually and forget to switch it on, that is scary too.
Greg's last post is what is all about.




You don't have to cut and splice the wire itself. You can push out the terminals from the relay holder using a small pin. Then you can cut off only the terminal and swage a new terminal and a new wire. In this way you can always rebuild your circuit to the original state when you want to.

 

Japthug, Please be Safe with the Typhoon Aproaching

Thank you for your patience in explaining everything to me.

How do I know if the relay is still good.

I am going to try and follow the recommendation that you, Greg, Paul and Spikepaga have passed on to me.

I have found that the older I get the less daring I am. Bothers me cause I was always the "Go To" when things had to get done. People knew I could figure it out!!

Again Thanks to the Group for Your Help!!!

Softball60 Paul

96 XJS 4.0L 2+2 Convertible
89 Merc 560SL
Every other British Sportscar Known to Mankind

 

Thank you for your care Softball60 Paul
My area is always relatively safe, but this time it's a big one, so I would have to be careful.

As ptjs1 Paul says, there is a thermo switch near the lower radiator hose. You could unplug it and jump the wire, which means the same as when the thermo switch contact closes, then fan should be running if the relay is good. Or, you could stick one side of a piece of wire into 85 (right below of the fan relay in the diagram above) terminal in the relay holder and connect the other side of the ground. This way you can bypass the thermo switch and lead current to the relay.