I live in South Florida and now that summer is approaching I am concerned as to how hot the operating temperature gets on my 97 XJR. I've installed a 170* f thermostat and without the air conditioning on the car will run in the mid 180*f -195*f range all day long. Run the a/c and I can just watch the temperature climb according to my Ultra Gauge. Starts out ok but get into some traffic and I can watch the temperature climb into the 205*f - 210*f range before I shut the a/c off, open the windows and sweat.

Am I being paranoid about a running temp above 200*f?

Any thoughts? Thanks

 

Suggest test to verify both fans run . With a cold engine as it has set for a while you could start the engine in the driveway and as you turn on the A/C switch to on you should see both radiator fans commanded to turn on . The big relay package is under the car below the air filter . There have been some service bulletins that modify the original factory wiring . Otherwise there is a specific second cooling fan temp " switch " other than the first cooling fan temp " switch " other then the other temp " sensor " that you see at the gauge and the ECU sees .

Thanks , Parker

 

Why?


That's the normal and desired operating range.

 

I believe the original spec was for 192F thermostat, at least it was for NA cars, I don't know if perhaps there was a different temp chosen for the SC ones. I'd recommend fitting whatever is specified.

The wiring change Parker refers to above was to address a too-often failing low pressure switch on the a/c system that was deleted sometime in MY96, I believe. After the TSB, the cooling fans run on "low" or in series at all times with key in "run" or position II I think it is called. This was to address a problem when the low pressure switch failed, the fans were sitting there in the "Off" position. Presently, they were commanded to "High" or parallel operation by the still-functional high pressure a/c switch. Instead of coming on and running at "High" they blew two 30A fuses in the left front engine bay fuse box, and stayed at "off."

The fans are controlled by radiator tank temperature and a/c head pressure. With the TSB mod, or with the later cars sans low-press switch. the fans are on low speed all of the time. If you still have a functional low-pressure a/c switch, and have the a/c secured, then it is perfectly logical why you see temps in the 180-195 range with your 170 T-stat. The radiator tank temp that activates the low-speed fan is 187F, I believe. I don't yet have the hi-speed temp committed to memory; reason would put it somewhere above 187; but probably near the 192 T-stat spec. So with a/c off, your fan would be off until you get to 187F.

 

I have no issues running at 180-195. My real issue is with a the a/c on it is running in the 205 - 215 range and is that ok? I understand that above 180 temp the thermostat is really a moot point. I just don't want my wife borrowing the car, running the a/c and dangerously running the temp up. Thanks

 

Again, that's well within the normal operating range of modern cars. The idea of 'cooler is better' is a myth left over from the '50s.

 

I agree with the above post and off my memory modern cars run at over 230 F . If you want peace of mind that both fans and your control relay module works you can just insert a paper clip in the coolent temp switch connector and the A/C pressure switch connector and watch the fans run without the engine running . Ref X300 Wiring Schematic figure 7.1 . 5 minute test . Low current/power circuit so no arcing or damage concern . Just verfied this test with Lady P . With the key in the on not start position the coolent temp switch is located an the radiator very lower left side . Contact the sockets for wire White Blue to Black will give you both fans , White to Black will give you the one left side . On the A/C switch it is the 4 wire connector located on the A/C lines on the aft firewall bulkhead . Contact the White Blue with either of the Black and you will get both fans . This test will only verify the relay module and the fan motors and not the switches themselves . You can clean and put some bulb grease on the connector for the under car relay module for I found the other connectors in the area corroded . You can post a sticker at the Coolant Overheat light to have your wife keep an eye on in service . Don't know if it will give you a aural warning . To verify that the Coolant Overheat light functions you can remove the connector ( don't pull out too much on the release tab for they are brittle ) on the right fan and over temp the engine and watch the light against your gauge although I would not do it myself , completely up to you knowing the risk but it gives you peace of mind that it will give you a warning .

 

Yup !

Now, if the temp keeps climbing up-up-up with no end in sight, that's a different story. But if 215ºF is about as high as she goes I wouldn't worry a bit.


Yes, two:

1) FWIW my XJR/6 ran 205-210ºF under similar circumstances

2) This is why Jaguar threw in the towel and joined so many others in calibrating temp gauges to give a fixed 'normal' reading until/unless the temp reaches a danger point.

Cheers
DD

 

Except there is no coolant overheat light....only the gauge. There is a coolant low-level light.

 

Just cut open the relay module and it was full of water where is wasn't suppose to be , not thin film oil . Corroded . Seal intact . So that's why the one low temp fan didn't run but both highs did . Couldn't repair / adjust relays in module . Relay Module LNA6702AA superseeded by LNA6702AB