Hi Fellas, I just collected my new toy yesterday. It's a 1994 XJR6 & so far so good. One thing is puzzling me, the radiator cooling fan runs continuously. Even when the engine is stone cold, as soon as I turn the key, the fan starts. Unplugging the engine coolant temperature sensor on top of the thermostat housing makes no difference, but it does stop if I unplug the cooling fan relay module, located behind the left hand headlamp. The dashboard temperature gauge stays very low as well. Does anyone have any thoughts, please?

 

Welcome, Tipptone.

It sounds like you might have located the problem already. What I would suggest is switching the relay with another of the same type that you are confident is working to see if the problem goes away.

 

Welcome to the forum, Tony. If your car is a X300, which I thought started in 1995, but may be 1994 on your side, the fans should run when the key is turned. Early models did not, but the factory did a modification, and the early ones were corrected.

 

Thanks for that Andrew, but unfortunately this unit is not just a relay it is some sort of module/relay with many pins.
Hi RJ237, it is 1995 MY, but late 1994 build. Anyway, are you saying that it is correct for the fan to come on with the key even when engine is completely cold? If that is so then yippee! I don't have a dreaded electrical problem at all. It only has one fan on the right hand side of the rad. The left hand side just has some rubber flaps to let air through with increasing road speed.

 

My 95 was also built in 94, but has two fans. Maybe US version is different, but many members have posted on the fan operation and yes, it should run with the ignition on even before starting.

 

Thanks very much RJ, I guess I just have a thermostat stuck open. Best regards, Tipptone.

 

The fans start running as soon as you turn the ignition key to where the dash lights up and before starting the engine.This is normal. There was a modification made to the XJ300 fans some time later. I suspect yours was modified. Keep in mind that the fans are designed to continue to run for some period of time after the ignition is switched off. This is controlled by a relay module
The most common problem people have experienced is that after the engine is shut off and the ignition key removed the fans continiously run thus draining the battery over time. These fans have 2 fuses located in the LH Engine Bay fuse box. F11 and F17

You should reach out to "SoGood" here who is located in Ireland and may give you some guidence.
I hope that helps you.

BigBossRadio Dallas TX formerly of Tramore Waterford

You may also want to check out the XJ300 E book at Jaglovers. Here is the link
Jag-lovers' Ebooks Book Index

 

PS With regard to the Dashboard Temp Gauge, it is notoriously unreliable so don't put too much store in it. You may want to install a new Temp sensor. Mine used to register in the blue range even after driving 100 mile in 100F outside temperatures.,

 

Thanks BigBoss. Just had a quick peek at the Jag-Lovers Ebook. Looks very helpful.

 

Glad that helped. You will get lots of help the........... Good luck with your new toy......

 

My XJ6 fans have never stayed on after the key is off.

 

Here is a a link to Jim butterworth's site...... He has many gems of wisdom for the XJ300 Jag owner..... You may want to check it out.......... and add it to your store of knowledge.
Hope it helps

Jaguar XJ6; Miscellaneous notes

 

Hi BigBossRadio, I've just settled down for the evening, it's 8.30pm here, & had a look at jimbutterworth''s site. There's food for thought! Thanks for the link.

 

you will need to replace this part as it is commonly missed out when addressing the non stop running of auxiliary fan for the radiator and condenser its a fan switch located on the left lower side of the radiator

 

Thanks for that Cool, but other members here have told me that it is correct for the fan to run continuously as long as the ignition is on?

 

And the other members are correct- as long as the Jaguar TSB change was made. The fans both run in low speed mode (they are connected in series), then switch to high speed mode when the engine heats up. (parallel connection of the fans)

 

I suppose my car must be UK spec with only one radiator fan. Does anyone know if this should start at slow speed & go to high speed when engine hot?

 

I

 

At the risk of confusing the situation, my understanding of the fan situation is as follows:
-The fans will come on at low speed if required to do so by coolant temperature.
-The fans will rise to high speed if low speed isn't lowering the temperatures sufficiently
-The fans may stay on for a period after the ignition is switched off if the coolant temperature is high enough
- The low speed fans will come on IF THE AIRCON IS ON, regardless of coolant temperature.
It is worth being aware that Very early X300s had a different aircon pressure switch, which controlled the fans separately.
Please also note that your car may have been modified. There is a popular modification described in another thread whereby the low speed fans come on whenever the aircon compressor clutch is engaged. I modified my car, and it cuts down a bit on fan operation, as in our climate, the compressor doesn't need to be running the whole time to maintain cabin temperature.

 

All you need to know about fan actuation can be found in the TSB's Bob put up in post #3: https://www.jaguarforums.com/forum/x...s-fail-148837/