[xj-s] Strange Aux Fan Behavior

When I turned the key yesterday, the auxiliary fan came on immediately;
before the engine even started. “How strange” I thought, and took a look.
One of the wires has a nick in the insulation, but I couldn’t mind anything
otherwise off.

I was in a hurry and decided “oh well, screw it - it’s really cold today so
if worse comes to worse, I’ll just unplug it”. Driving around through the
day and night, I experienced nice running temps. She performs great when
cool like that. The fan seemed to operate properly, though kicked in at
lower temps than normal from time to time.

Stuck/sticking thermostat somewhere?

Gordon

'88 XJ-SC (Lucas CEI) Bagheera (46,000 miles)
'95 XJ6 (VP) Kyriell (128,000 miles)
www.myjags.net
Alexandria, VA US

// please trim quoted text to context only

This happens every so often on my car, too.

My car and I imagine yours as well is wired so the fan comes on with the A/C
compressor. If the engine was shut down with the compressor engaged then
it’ll be engaged when the engine is restarted…until the climate control
readjusts.

Doug Dwyer
Longview, Washington USA

When I turned the key yesterday, the auxiliary fan came on immediately;
before the engine even started. “How strange” I thought, and took a look.
One of the wires has a nick in the insulation, but I couldn’t mind
anything
otherwise off.

// please trim quoted text to context onlyFrom: “Gordon Vivace” gordon@myjags.net

My car and I imagine yours as well is wired so the fan comes
on with the A/C compressor. If the engine was shut down with
the compressor engaged then it’ll be engaged when the engine
is restarted…until the climate control readjusts.

AHA! And that’s exactly what happened because I noticed immediately that
the heater was on and I thought “that’s strange … I always turn that off”.
Except … The engine wasn’t started. I always turn the key to “on” for a
couple seconds before cranking it and the fan came on then. Same thing?

Gordon

'88 XJ-SC (Lucas CEI) Bagheera (46,000 miles)
'95 XJ6 (VP) Kyriell (128,000 miles)
www.myjags.net
Alexandria, VA US

// please trim quoted text to context only

Gordon,

Could be the fan thermal switch… mounted in the water pump inlet housing.

Ed Sowell
76 Xj-S

When I turned the key yesterday, the auxiliary fan came on immediately;
before the engine even started. “How strange” I thought, and took a look.
One of the wires has a nick in the insulation, but I couldn’t
mind anything
otherwise off.

I was in a hurry and decided “oh well, screw it - it’s really
cold today so
if worse comes to worse, I’ll just unplug it”. Driving around through the
day and night, I experienced nice running temps. She performs great when
cool like that. The fan seemed to operate properly, though kicked in at
lower temps than normal from time to time.

Stuck/sticking thermostat somewhere?

Gordon

// please trim quoted text to context only

I’m thinking the fan temp switch.
.
Jamie & Dru - Everett, WA
88 Series III V12 VdP - Roxanne
89 XJS V12 Convertible - Butch
Jaguar Owner’s North American Tour - http://jonat.org
April 15, 2004 - July 4, 2004
.----- Original Message -----
From: “Gordon Vivace” gordon@myjags.net
Sent: Monday, November 10, 2003 5:57 AM

When I turned the key yesterday, the auxiliary fan came on immediately;
before the engine even started.
Driving around through the
day and night, I experienced nice running temps. She performs great when
cool like that. The fan seemed to operate properly, though kicked in at
lower temps than normal from time to time.
Stuck/sticking thermostat somewhere?
Gordon
'88 XJ-SC (Lucas CEI) Bagheera (46,000 miles)
'95 XJ6 (VP) Kyriell (128,000 miles)
www.myjags.net
Alexandria, VA US

// please trim quoted text to context only

Well, I’ll be darned! It’s amazing how much you can learn on these Lists.
The A/C link makes total sense, I just didn’t even think of that. I’ll keep
it in mind from now on though.

Good show Doug!
.
Jamie & Dru - Everett, WA
88 Series III V12 VdP - Roxanne
89 XJS V12 Convertible - Butch
Jaguar Owner’s North American Tour - http://jonat.org
April 15, 2004 - July 4, 2004
.

Doug Dwyer said:

My car and I imagine yours as well is wired so the fan comes
on with the A/C compressor. If the engine was shut down with
the compressor engaged then it’ll be engaged when the engine
is restarted…until the climate control readjusts.

AHA! And that’s exactly what happened because I noticed immediately that
the heater was on and I thought “that’s strange … I always turn that
off”.
Except … The engine wasn’t started. I always turn the key to “on” for a
couple seconds before cranking it and the fan came on then. Same thing?
Gordon
'88 XJ-SC (Lucas CEI) Bagheera (46,000 miles)
'95 XJ6 (VP) Kyriell (128,000 miles)
www.myjags.net
Alexandria, VA US

// please trim quoted text to context only----- Original Message -----
From: “Gordon Vivace” gordon@myjags.net
Sent: Monday, November 10, 2003 7:03 AM

A few more possibilities:

How about a stuck relay? Or a short in the temp switch wiring? Or…
Don’t these era models have some kind of a diode device that is supposed to
keep the aux fan circuit alive after shutdown? If so, can’t a faulty one
cause the fan circuit to be hot when the ignition is switched on?

Gary
94 4.0L Convertible
San Jose, CA----- Original Message -----

I’m thinking the fan temp switch.
.
Jamie & Dru - Everett, WA

// please trim quoted text to context only