X300 engine cooling fans on all the time??

[fast cars]

The fans seem to stay on all the time and only switch off when the fuse is removed in the front ns engine bay fuse box, can someone tell me where I would find the fan switch and relay to diagnose the problem, or is it something else?

Thanks
Danny

[Manicminer]

Do you use the air-con a lot? They quite often use the rad fans to draw air over the condensor when the car isn't moving.

[fast cars]

Hi ac has been disconnected - the belt that is as the compressor has seized

[Jaguar steve]

IIRC the X300 cooling fans should have two operating speeds. Slow when the a/c is engaged and fast when the coolant temperature is too high.

The electrics don't know your compressor is siezed and the belt disconnected so it may be you have a fault calling for the fans to run as the system thinks it's working - even if it's not.

Suggest you try pulling a few fuses to see if you can isolate the cause.

There was a modification to the cooling system fan speed control involving some bypass wiring featured in the JEC magazine a long time ago - I can't remember the details but might be worth some Googling.

[fast cars]

Hi Steve, thanks again for the info, do you know where the fan relay lives? I have so far found the fuses that control the 2 fans but no others, also note that with fuses in situ the fans run immediately with the car engine off and cold, have tried ac switches but this does not change anything, also unplugged the sensor cable to thermostat switch on the radiator but fans remain on.

Thanks

Danny

[Jaguar steve]

Fraid I can't remember exactly what's normal for X300 fan operation. One thing I can suggest is make sure there's enough coolant in the system to rule out the possibility of localized overheating causing the fans to run continiusly and check the thermostat is not jammed shut and trial and error swapping relays around. Might be worth a google to see if anybody's posted info on the modification and see if you can get hold of a workshop manual CD, but even that won't tell you how the fans should be configured to work


Sorry, that's not very helpfull is it.

[entwistlecymru]

An early Jaguar technical service bulletin called for mods to the operation of the fan so its normal on early cars for one of the fans to run continuously when the ignition is turned on. There's more info on jaguarforums.com - I found the info there just after I bought my XJR, and it turns out its quite normal!