Cooling fan

[MichaelSB]

Am I correct in thinking the electric fan on the drivers side is a gearbox fluid cooling fan? And if yes is it normal for it to run after the engine is turned off or should I be concerned?
Thank you

[Tintin]

AFAIK the electric fan is not dedicated to the gearbox fluid but is part of the general cooling system (others will no doubt comment). In normal operation the engine driven fan and forward motion of the car provide sufficient cooling; the electric fan operates in exceptionally hot conditions and can run when the engine is turned off until the coolant temperature falls to below 90 degrees. If the electric fan operates regularly there may be an issue of overheating.

Under what conditions does your fan cut in Michael?

Robbie

[davidr]

As Robbie says, the electric fan is there to give additional airflow through the cooling pack when necessary. Yes the auto gearbox fluid does go through a chamber on the side of the radiator for cooling but that's not the reason for the fan.
Reasons for insufficient cool air flow could be slow (or no) forward speed or the aircon condenser radiator (which sits in front of the cooling radiator) giving off a lot of heat if the aircon is working hard or the radiator airflow being blocked. It can also come on when the car is switched off hot as the heat soak and lack of circulation will raise the coolant temperature so the sensor sets off the fan until it drops down again.
In my experience, this fan very seldom runs. In fact, I hadn't realised that my own one had seized completely until I was refurbishing the coolant system and tried turning it by hand!
The radiator can be pretty useless before you will see much visible deterioration.
I put a thread on here about my own radiator fix. I started looking because I could see a small area where the fins were breaking down. Once I got it out of the car I could see that the bottom third was gone! Despite that, I had driven the car all round the south of France with no issues!
If the fan is running a lot I would look into that more deeply.

[MichaelSB]

Hi Guy's
The temperature gauge reads normal and no other sign of over heating, is the a sender unit that brings on the fan that could be faulty as it seems to come on each time I take it for a drive and then switch it off, I can't be sure but I may have heard in running when driving today.
My a/c is not working but I have someone looking at that tomorrow
Michael

[ptjs1]

Michael,

There is a thermoswitch mounted in the LH tank of the rad. Try backprobing the switch and see how the resistance changes as the car warms up. You can then verify if the thermoswitch is at fault.

As others have ssid, you really shouldn't have it running unless under extreme temp conditions.

Psul

[oldtimer]

Michael,
Examine the gap between the evaporator and radiator, it is surprising at the accumulation of leaves, hay and matted material that collects there over time . Not too sure of the visual access, it may be necessary to remove the top cover !

Question :- David R , can you see up between radiators from beneath ?

[MichaelSB]

I will have a look today as I have my a/c guy coming to service a/c and hopefully get it working.

[davidr]

Michael,
Examine the gap between the evaporator and radiator, it is surprising at the accumulation of leaves, hay and matted material that collects there over time . Not too sure of the visual access, it may be necessary to remove the top cover !

Question :- David R , can you see up between radiators from beneath ?

Oldtimer - no you cant see up between the two radiators from below as they are mounted on a cross-rail and the under-tray will be in the way. The best way to do it is to take the top rail off. This is easy enough with fixings on both wings. The only hard bits are the 1/4" nuts that hold the receiver/dryer bracket to the cross rail. These will be rusted and will shear very easily. I know that from bitter experience!

Michael - good luck with the aircon! Hopefully its just a case of a re-gas and you're up an running again. However in real life its often not that simple and you will have a leak somewhere. Most common areas for leaks are the condenser radiator (relatively easy to fix) or the evaporator which is a PITA to fix as the whole dash has to come out. The front seal of the compressor can leak - you'll see a spray of oil thrown off it if it does. Another likely candidate is the alloy pipe that runs up the inner wing on the drivers side. These corrode and develop small holes. If you've dye in your gas then you will see it. The bad news is that these pipes are no longer available. I had to mend mine and I did it by getting an earlier version (which is available) and having a boss welded into it for the pressure switch.
One other thought, if the compressor clutch will not engage when you have the system back up to pressure then you can kick start it by taking the plug off the pressure switch and shorting it across. I don't know why that is but its what I have to do to mine!

[Tintin]

David R has covered the A/C failure modes, but co-incidentally I have mine booked in for a replacement compressor next Tuesday. The front seals have failed - easy to detect even with no dye as David says, because the oil is flung off in the space between the rad and engine - if you wipe the underside of the top hose you will see it. SNGB offer two replacement compressors at vastly differing prices - they assure me that they are identical units, only one comes in a Jaguar box and the other doesn't! I went for the lower priced Sanden unit (not a re-con) and it arrived yesterday. Looks the business - fingers crossed!

Robbie

[steve_m]

Doesn't the auxy fan also come on when the aircon is engaged?

[davidr]

Doesn't the auxy fan also come on when the aircon is engaged?

Yes and No!!
Early cars had that as standard. Later cars then didn't for some reason better known to Jaguar so on my 1989 V12 for example I have wired in a feed from the compressor clutch to the fan (via a diode so the clutch doesn't engage when the fan is running for cooling only) so the fan comes on when the compressor is running to pull more air through the cooling pack.
I can't remember whether the Celebration puts the fan on when the clutch is engaged. I don't recall noticing it ever doing it.

[Tintin]

I can't remember whether the Celebration puts the fan on when the clutch is engaged. I don't recall noticing it ever doing it.

Don't think mine does it either - in fact I can't ever remember the fan coming on at all. I don't suppose there's any way to test it under operational conditions unless you remove the viscous fan and let the engine idle to the point of overheating. Not something I'm keen to do though.

Robbie

[PaulGover]

The fan on my '91 V12 usually comes on sporadically in hot weather, and usually runs on at switch-off for a couple of minutes, and AFAIK that's normal. Depends on how much slow speed driving you do - at anything much above 40 mph, ram effect will blast enough air through to cool anything, but in town, and particularly stuck at the lights, there's not much movement, so a bit of extra cooling is beneficial.