Notice on my XJR6 that fans running fast too long after
engine shut down, and battery now fully discharged. Car
battery consequently dead this am. Connected battery
charger and fans both running on slow speed. Aaagh- even
without key in ignition???. So guess must disconnect white
connector at Engine bulkhead RH drivers side in order to
recharge battery by stopping fans…? Will engine be safe
to run in winter without fans…think AC needs them too.
Fault appears to have started after engine oil filter
changed in shop. Did they touch something or coincidence?
Wondering if have:
faulty radiator thermostat or switch (must check location)
faulty fan control relay behind LHS outer headlight ( will
try to check)
A third factor my ignorance is allow to self-conceal
Any ideas/advise guys?
Thanks–
Ant XJR6
Kent, United Kingdom
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
In reply to a message from Ant XJR sent Mon 10 Oct 2016:
Update: removed fan fuse No 11 from LHS front wing fuse box
and no fans operating. There is only one blue relay in this
fuse box. Now able to recharge battery.
What to check or replace next?–
Ant XJR6
Kent, United Kingdom
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
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In reply to a message from Ant XJR sent Mon 10 Oct 2016:
I had problems with the fans not coming on at high speed
and tracked it down to the relay under the near side front
headlights. A silly place to put a relay as it gets a bit
of a hard life.
I appreciate it not the same problem but you can pick them
up cheaply second hand and it might be worth a try–
Lifeboats
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
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In reply to a message from Lifeboats sent Tue 11 Oct 2016:
Thanks Lifeboat
Based on archives and other forum info - looks like my
fans-on-all-thetime-even-when keys out and left overnight
problem is either the cooling fan relay LNA 6702AB behind LH
front wing you mention or the fan thermo switch DBC10013
screwed into left side of radiator. How do I test for which
is the culprit? Perhaps need volt meter.
Hope its not the ECU, as all other services work fine. I’m
driving fanless by removal of Fuse No 11 on LH wing fuse
box. Fuse No 17 removal has no effect.
With keys out and engine cold, fans both run if I replace
Fuse 11. V spooky.
Might as well replace the 4? rubber radiator mounts at the
same time and. Guess rad has to have coolant drained if
replacing ther fan switch.
Now need to check archives to learn how to take off LH inner
wing plastic shroud.Thanks for any advice, people–
The original message included these comments:
I had problems with the fans not coming on at high speed
and tracked it down to the relay under the near side front
headlights. A silly place to put a relay as it gets a bit
In reply to a message from Ant XJR sent Wed 12 Oct 2016:
Sorry I can not help with the rad switch, but if you are
down there look at the air con rad in front of the engine
rad, have a look at the mounting rubbers two top and two
bottom, mine were all shot and the rad was moving about
which would damaged the air con pipes eventually. The top
panel over the rad, can be a bit of a pig, due to rusted
fixings, one of mine refused to move and had to be drilled
out.–
Lifeboats
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In reply to a message from Ant XJR sent Wed 12 Oct 2016:
Wouldn’t a thermoswitch require power to be considered
faulty?
I vote for the relay.–
The original message included these comments:
problem is either the cooling fan relay LNA 6702AB behind LH
front wing you mention or the fan thermo switch DBC10013
screwed into left side of radiator. How do I test for which
In reply to a message from uncle sent Wed 12 Oct 2016:
Hi Uncle
My local Jag guru plumps for the rad thermo switch but he
hasn’t seen the car & problem yet. Says it was the thermo
switch on an Alfa he fixed last week…Guess I could try
fiddle with its earth wire if I can get access without a
ramp. I’ll report back when prob solved next week. An
over-confident non-mechanic Polish friend claims he can fix
the swtich by dis-assembling and cleaning. Sounds too good
to be true…–
The original message included these comments:
Wouldn’t a thermoswitch require power to be considered
faulty?
I vote for the relay.
In reply to a message from Ant XJR sent Thu 13 Oct 2016:
Do you have the jumper wire on your switch? This would make
your fans run all of the time with the ignition on. But
with the ignition off, the switch, with or without the wire
would have nothing to handle.–
The original message included these comments:
My local Jag guru plumps for the rad thermo switch but he
hasn’t seen the car & problem yet. Says it was the thermo
switch on an Alfa he fixed last week…Guess I could try
In reply to a message from uncle sent Thu 13 Oct 2016:
Uncle
After removing and then replacing Fuse 11 in LH front wing
fuse box which used to stop and return fans…the fans now
do not come on at all, irrespective of fuse 11 or switching
AC on. Car drives fine without fans in this cool
weather…next week hope to find the cause of prob.
My XJR is an early 1994 car and cannot see any jumper on
switch connection at bulkhead…–
The original message included these comments:
Do you have the jumper wire on your switch? This would make
your fans run all of the time with the ignition on. But
Did you ever find out what the problem was? My car has developed the same or similar issue. The fans run way too long, but do stop after a couple of hours. I have unplugged the thermal switch mounted at the bottom of the radiator, but I am not 100% sure it is really the cause of the problem. When I plug it back in the next day, the fans don’t start.
Maybe the switching temperature has become to low? Or it is just sticky?
I had the same problem, swapped the relay under the headlight, checked the thermal switch and everything was still the same. I unplugged the pressure switch on the air conditioning line at the bulkhead and the fans stopped. Swapped out that pressure switch and it cured my problem.
My car stopped doing it, so I forgot all about the problem and this thread. But I will certainly have a look at the pressure switch when it happens again.