Any thoughts about wiring the auxiliary fan to a rocker switch inside the cabin? I'd like to be able to switch the fan on instead of relying on the temp. sensor.

 

You wouldn't be the first


Cheers

DD

 

The only problem with that is, what if someone else drives the car? Or what if your attention is elsewhere, such as an intense conversation with a lovely passenger or phone call or just spacing out enjoying the scenery?

A simple suggestion would be to order and install one of these:

Jaguar XJS V12 Auxiliary Cooling Fan Switch Upgrade

It causes the fan to come on at a lower temperature, and works quite well.

 

Most here have not had the best of luck with that particular supplier.

 

Good to know. That's the only item I've ever ordered from that supplier, but didn't have any issues. It should be available from other suppliers.

 

Good point

I assumed.....heh heh, bad, I know....that the manual switch would supplement, not replace, the existing temp switch


Cheers
DD

 

Replacing the OEM fan with a modern top quality fan is probably the most important thing to do, in addition to adding a manual switch. As Doug said, it is not a good plan to remove the original circuit in case you forget to manually activate the fan.


Also, my feeling is that the fan should also be on whenever the aircon compressor is on, and this is an easy fix if your particular model does not do this. Jaguar changed their minds about this from time to time. Mine comes on OEM 100% with the aircon.
Greg

 

Just following up on this old thread, I have a 1982 V12- the auxiliary fan seems to run permanently when the aircon is on, and since the Delanaire system is automatic or nothing it is alway son when the heater/aircon is on. However, my ac has stopped working now (together with a horrible alternator belt squeal...) and I have noticed *no* auxiliary fan cut in. This is perturbing given the reputation of the V12 and also given that I have a 42 year old radiator & an abnormally low (i.e. not believable) dash temperature reading. The heating and thermostat work.

1. Is it normal to have no aux fan cut in but continual running with climate control?
2. If not, assuming I can wire the relay to the temp sensor on the water pump, is it recommended to upgrade the aux fan?
3. Does that same thermal sensor run to the dash display (I believe I have grounding issues as tacho, fuel gauge and speedo are erratic)?
4. Would you replace and/or upgrade the temp sensor?
5 . I dont want to budget for new radiator or main electric fan yet as I have other upgrade/restoration tasks in the immediate future, but maybe later.

Thanks a lot!
Matt
1982 HE

 

There is a diagram out there that ties that aux fan to the AC Power. Turn on the AC, and the aux fan turns on.

This mod does not change the way the original fan was designed to run, so even if the AC is off, and the coolant demands that the aux fan comes on, it will.

Much better than a rocker switch, in my opinion, which can be forgotten.

 

The aux fan does not appear to cut in at all when my AC is off (also, I had understood from other posters that it is not always the case that the aux fan runs continually whilst the AC is on in all models).

 

The aux fan isn't designed to run continuously while the AC is on in any models. The wiring modification adds that feature to the way the fan is set to operate on all models.

With or without the mod, the aux fan should come on when the coolant reaches a certain temperature, whether AC is on or off. The mod simply adds a second way to activate the aux fan, which would be whenever the AC is turned on.

 

Not quite correct.

On many of the V12s, at least until 1989-ish....that's when some of the fan and compressor circuits were changed....the aux fan would, by design, come on whenever the a/c compressor was engaged. And....the climate control system was designed so that the compressor was engaged in all modes: cooling, heating, blend, defrost. So, for all intents and purposes, the aux fan was operating at all times unless the climate control was set to "off".

Cheers
DD

 

I recall that the temp switch for the fan is calibrated to 94ºC. Your coolant might not be getting hot enough. Or....there could be an actual fault to trace and repair.

Cheers
DD

 

Thanks Doug.

 

Standard OEM fan switch on the V12s He pre facelifts cuts in at 85°C.

 

I definitely have an issue then as I was doing a lot of traffic driving over the weekend and no fan../