Hi Guys, I usually spend most of my time on here on the XJ40 and E.Type sections, I’ve never owned or looked closely at an X300 engine bay.
Today I had a complete stranger call at my house " I was told you fix Jaguars, can you help me " he said. I politely explained that I only fix and work on my own cars but offered to have a look. The car is a recent purchase and he was told by the PO that it was recalled by Jaguar earlier in it’s life and they fitted a link in a plug so the fans run all the time regardless of coolant temp. On the LH side of the engine bay looking from the front there was a white plug with a link wire across two pins, when it’s removed the fans stop.
I’m fairly sure the fans are not meant to run continously from a cold start, is there a common fault that you guys might know about on a X300 relating to the fans NOT coming on indicating somebody else has by passed the problem by fitting this link ?
He also said the temp needle barely moves out of the cold zone even in traffic, I realise the fans being on all the time wouldn’t help but I suggested he gets a new thermostat first seeing as it’s cheap and relatively easy to change and he doesn’t even know if it hasn’t already been removed. He said he’ll fit a thermostat and call back to see if I’ve managed to find out more info on the problem.
Cheers Guys.
I forgot to mention the CTS looked like it was new and recently changed, he said he hadn’t changed anything, so it looks like somebody else has recently been trying to track down a problem with the cooling system.
The link was added on early models to prevent the fuse blowing, on my ’97 I used to plug it in in summer and remove
it during winter.
There is a TSB on jagreair.com
[quote=“Neil_Maldon, post:2, topic:416714”]
There is a TSB on jagreair.com
[/quote]…or it might be jagrepair.com 
A big thank you Neil and Jagfab, that is a really useful link, I found the TSB and it’s helped me understand how the fans are wired and why that plug is linked out.
I always hated this “issue/feature” with the constant running cooling fans. I reluctantly do the same as others cabin switch, plugin/summer unplug/winter in my 95 x300. Does anyone know how to set up these fans to run like a conventional normal cars system. This whole x300 cooling fan issue is what we did when electric fans were in their late 40’s infancy.