[xj40] HELP! Ongoing problem with 1989 jaguar A/C-blows fuse-circuit

XJ40
1

I bought my 89 in 2004 and the a/c worked fine for three
years, and then I had to replace the blower motors and they
worked fine for a long time. Last year I started getting a
problem with the a/c when turned on would blow the fuse on
the passenger side, which it says is connected to a/c
clutch…it was intermittent and was more likely to blow on
hot days…so, we assumed it was the compressor, and I went
through replacing with a new compressor, new switch, new
dryer, and whaever else was needed - expansion valve I
believe. This was all new parts that came recommended. So, I
had the work done in Las Vegas while I was temporarily moved
there, and the shop installed all the new parts and the
circuit failure stopped, and the fuse stopped blowing, and
the a/c worked…then about three months later, all of
sudden - no cold air one day, just out of the blue. So,
eventually after going through the winter in Cali and not
really needing the a/c and knowing the parts were under
warranty for a year, I got the money together and had a shop
in Pasadena,CA look it over and determined faulty parts-bad
a/c switch,etc…so, after $300 more dollars of labor the
replaced under warranty parts were installed and I had cold
air again…then about a month ago, guess what…one day, the
circuit failure starts up again…and it just seems like
under hot conditions this car’s a/c cant hold up…but its
weird because I went through three hot texas summers and the
a/c worked fine…my trusted Jag mechanic for many years in
Pasadena,CA wont work on a/c…has anybody seen or had this
problem and figured out what exactly is happening when you
get the circuit failure coming on and the blown fuse when
you switch on the a/c? Please educate me, I’ve now gone in a
complete circle in a year and a half dealing with this and
its hotter than hell right now in LA! THANKS TRUSTED FORUM
(MECHANICS HATE IT WHEN YOU TELL THEM YOU READ OR
COMMUNICATED ON A FORUM LIKE THIS, BUT I ALWAYS TELL THEM
THAT JAGLOVERS KNOWS A LOT!)–
DavidPlank89VandenPlas
Los Angeles, Ca, United States
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2

In reply to a message from daveplank sent Wed 2 Sep 2009:

Dave,

Sorry to hear of your travails.

First, lets be clear here - exactly which fuse keeps blowing
in the passenger (right side) fuse box?

If it is fuse #11 which serves the air conditioning
compressor, that fuse also serves the auxiliary electric
cooling fan in front of the radiator.

It is entirely possible that the latter is your problem,
because it only switches on to provide additional cooling
when the coolant temperature is high in hot ambient
conditions - just the very same conditions which persuade
you to switch on the air conditioning.

With infrequent / no use during cold weather, the fan motor
seizes up. The next time it is switched on, it overloads the
circuit and blows that fuse #11 in the right side fuse box.

Check that the auxiliary fan is free to rotate - stick a
pencil through the grille and flick the fan blades (ignition
off of course!). It should spin freely. If it is seized or
if it is sluggish, the combined load of that fan added to
the load introduced by the compressor clutch when you switch
on the A/C is enough to blow the fuse.

Good luck (at least, that is a really cheap fix!)–
The original message included these comments:

Pasadena,CA wont work on a/c…has anybody seen or had this
problem and figured out what exactly is happening when you
get the circuit failure coming on and the blown fuse when
you switch on the a/c? Please educate me, I’ve now gone in a
complete circle in a year and a half dealing with this and
its hotter than hell right now in LA! THANKS TRUSTED FORUM

–
Bryan N, '91 Sovereign 4.0 L, RHD
Cambridgeshire, United Kingdom
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
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3

In reply to a message from Bryan N sent Thu 3 Sep 2009:

thanks Bryan. I searched forums after my posting and
remembered looking into the auxillary fan issue when the
circuit fuse first started blowing last year. I put a stick
in through the grille, and the fan spins ok. When the
circuit fuse, it is #11, first started to blow back last
year, it was a gradual thing, whereas,the a/c might blow
cold while you’re driving for 15 minutes, and then
eventually the fuse would blow, which makes you feel like
the compressor cant take the load for a longtime and blows
the fuse…so we pinpointed the compressor, and I eventually
had a shop tell me that the problem was a bad switch but I
had already also bought a new compressor and o I couldnt get
a full refund, so I had them install everything…new
compressor, new a/c clutch/pressure switch, dryer,exp
valve.etc…and although my original a/c compressor blew
cold air through two hot texas summers, I am now on my
second set of parts for the air compressor and
switch…replaced under warranty back in May/June…what I
really want to find out is what actually causes the circuit
fuse to blow, because I’m being told by the mechanic that
put the parts in last, ‘‘well, then you have an electrical
issue, I just installed the parts you gave me…’’ and he
doesnt want to deal with me anymore, but I think he owes me
a checkup under labor warranty…I cant believe the air
compressor and switch keep going bad…unless maybe the
aftermarket that they sell, just dont do the job of the
original? The other day, I had the a/c running for 20
minutes with no problem…then I turn off the engine…come
back out in an hour to go for a cruise, and as soon as I
turn on the ignition, wham!..the damn #11 fuse blows and I
get circuit 1 failure…could it be connected to the a/c
switch on the inside panel, since it is sometimes
intermittant? I wouldnt think so, because it has to be the
a/c con clutch somehow thats blowing the fuse connected to
it//right?–
DavidPlank89VandenPlas
Los Angeles, Ca, United States
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4

In reply to a message from daveplank sent Thu 3 Sep 2009:

Dave,

Well, your mechanic is quite correct in saying that you have
an ‘electrical issue’ - that’s why it is blowing the fuse! :wink:

The question is, which of the three circuits served by that
fuse #11 - the aircon compressor clutch, the auxiliary
cooling fan or the under-bonnet lights is the cause?

It cannot be the aircon compressor itself because that does
not put any electrical load on to that circuit when it is
operating but it may be the compressor magnetic clutch or
the wiring to it.
[You mention ‘after-market’ parts. I assume it is still a
Sanden compressor and clutch?]

If the wiring to the clutch is suspect, it may be the
Green/brown wire which carries 12 volts from the clutch
relay (right side radiator support, green base) to the
clutch itself. There are warnings in the book to be careful
about the run of that wire to ensure that it doesn’t get
snagged on the compressor pulley / drive belt and grounded -
which will of course blow that fuse #11.
Alternatively, it could be where that Green/brown wire is
spliced to thread its way back towards pin 21 of one of the
25-way black connectors on the EMS ECU under the dash which
carries 12 volts but is only ‘live’ when the A/C compressor
clutch is engaged. Again, any grounding of that wire will
blow fuse #11.
Another alternative (there are many!) is that the auxiliary
cooling fan circuit is at fault. The easiest way perhaps to
eliminate that circuit is to temporarily remove the fan
relay (black base on that same right side radiator support)
and drive the car with the A/C on full blast to see if the
fuse #11 still blows. HOWEVER - do be careful to keep an eye
on the engine coolant temperature gauge to avoid
over-heating. Do not run the engine and the A/C with the car
stationary for extended periods - you need airflow through
the radiator to keep the coolant temperature within limits
and the mechanical fan needs RAM air to help do that.

If the fuse doesn’t blow with that auxiliary fan
inoperative, perhaps you have isolated the cause to that
circuit.

One other more remote alternative is a short in the
under-hood light circuit. As you probably know, Jaguar opted
for a ‘ground switched’ system to operate things and the
under-hood lights are no exception. From that fuse #11, a
Brown/purple wire puts 12 volts battery power (‘always hot’)
on to those under-hood lights. Those lights only illuminate
of course when the main car lights are switched on - but
that is done by grounding the other side of the bulbs
through the auxiliary side-light relay (nothing to do with
the auxiliary cooling fan BTW). However, if that
Brown/purple wire upstream of the lights grounds somewhere
en-route, bang goes fuse #11.
I can’t see any relationship between those under-hood lights
and switching on the A/C (apart from fuse #11) but I believe
in coincidence sometimes! Check the wiring to those
under-hood lights - particularly where they pass through the
grommet in the front of the engine bay. Sometimes they fray
there.–
The original message included these comments:

original? The other day, I had the a/c running for 20
minutes with no problem…then I turn off the engine…come
back out in an hour to go for a cruise, and as soon as I
turn on the ignition, wham!..the damn #11 fuse blows and I
get circuit 1 failure…could it be connected to the a/c
switch on the inside panel, since it is sometimes
intermittant? I wouldnt think so, because it has to be the
a/c con clutch somehow thats blowing the fuse connected to
it//right?

–
Bryan N, '91 Sovereign 4.0 L, RHD
Cambridgeshire, United Kingdom
–Posted using Jag-lovers JagFORUM [forums.jag-lovers.org]–
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1 Like
5

Sorry to resurrect this old thread but I am having very similar symptoms. Fuse #11 blew. I disconnected the auxiliary fan and had no issues with the fuse. Ran 12v into the aux fan and it didn’t run. Ordered a replacement spal fan as I couldn’t find the original.
Wired it in and still have the same issues. It will run with 12v applied separately. I’ve looked at the wiring and checked the ground and can’t find any issues. Is there a way to track down what appears to be a wiring issue or bypass it? I’ve considered wiring it to a switch that I could use when I needed it if I can’t find the issue.