Hi Lads, even when the engine is not heating (and I live in Miami) it seems like one of the cooling fans is not working. Could be the thermostat be responsible for that? What other thing could it be? Is it just hard to believe to me that a fan just stop working. If that the case, is it necessary to replace both? Is it possible to repair them? Thanks!

 

There are a couple of things that influence the fans operating but the thermostat would only get involved when it caused overheating of the engine.
There is a temperature sensor on the top water manifold that provides info to the fan controller and the ECU. There is a fan controller mounted on the left upper side of the radiator that turns on/off the fans. Lastly the ECU when seeing the air conditioner runner turns on a fan.
You can download the electrical diagrams for your vehicle from JagRepair.com - Jaguar Repair Information Resource. Then you can jumper out the fans one at a time providing voltage to isolate a bad fan.If the fans test good then you can test for voltage signal from the temp sensor. If it is good then you most likely have a bad fan controller.

 

As pointed out already, turn the air conditioning on and see if the fans run. Both should run. In the later cars, I believe the fan controller (located on the fan shroud) continuously controls the fan speed with PWM. This is no longer a high/low type of thing. I also believe the fans are both supposed to run at the same speed at all times.

 

hmmmmmm.........I just drove my car for 15 mins to warm it up, opened the bonnet , turned on the AC and neither fan moved at all. Let it idle for a few minutes and still nothing. Come to think of it I have never heard the fans start . Just to be clear....The fans should start when you switch on the AC in a warmed up car ?

 

To my knowledge, the fans turn on the moment the a/c turns on, independently of the coolant temperature. The idea is to help evacuate the heat from the condenser and have cold air in the car at any speed.

 

well..I'll surely have to check it out because neither of mine even twitched.....it is just above 10C here though....so that may be affecting the situation

 

The ECU doesn't care what the temp is outside if A/C is on fans run. Sounds as though the controller needs to be replaced. But first jumper power to the fans and make sure they actually run.

 

as soon as I figure out how to jumper the fans I will. They both turn freely by hand so they are not seized at least

I know that the previous owner replaced the thermostat and was a bit of a twit ...is the fan control connected in any way to the thermostat area ?

 

Barry,
Something just occured to me, not sure if mentioned above. The fans do not always come on simultaniously. Just wanted to be sure you knew that.

I just checked a conversion hoping that 10C is below minimum AC operating temp. Looks like that is 50 degrees Farenheight, fan should come on with the ac switched on.

Do you have a POT (potentiometer aka variable resistor) and several feet of wire? You could easily immitate virtually any engine temperature by puting the pot into the connector that goes to the water temp sensor. Using your OBDII you will see that various resistances produce differnt temperatures. Once you hit (gosh what was it 190?) fan #1 comes on. In case this wasn't clear -the car measures resistance at the temp sensor and translates it into a temperature. You can fool the car into thinking the coolant is any temperature by changing the POT/resistance. Like I said you can monitor it on your OBDII display and listen for fans turning on.

I think the POT is in the 100 - 200 ohm range, but that's 2 year old memory. Just ask if you want me to run out and do a quick measure should you go this path. I've got one in my tool kit courtesy of WhiteXKR and his excelent Real Guage.

John

 

Not in the way you are implying. As previously stated one fan, on my car I believe it is the left, or drivers side fan, will start the instant I turn on the A/C, from both a cold start, where I have not started the car in over 24+ hours, to the dead of winter. Which last year it was -8 around these parts due to that stupid stagnant cold front that parked over the PNW; I accidentally hit the A/C button one freezing night, and the fan roared to life, so if the A/C is on the fan comes on.

However, if you actually try to 'call' for A/C when it is this cold the ECU will lock out the compressor, but I believe the car uses the A/C to defog the windshield in the winter. The Environmental Controls in the Cockpit can be used to interrogate the A/C system and reset the compressor if it is locked out, however, I no longer have that procedure or my manuals loaded onto my computer any longer, after a reset cleared them off and I cannot find my thumb-drive. Search for A/C diagnostic procedure or something similar, the procedure is in the forum archives somewhere, maybe there is a code stored that can give you a clue.

From 2003 and up the fans are variable speed, with the right fan coming on and off, and speeding up and down when the car reaches operating temperature matching speed with the other fan; in an overheat situation you would know if both fans were operating at high speed to combat overheat by the sheer sound; Thank God I have never heard it personally on my car, but I saw and heard it on an XK8/R, on a YouTube video once and it was pretty terrifying to say the least, lost that bookmark during the reset also or I would post the link. Have you checked all fuses and relays, and the large gauge wire and connector that is mounted on the left (DS) top of the radiator for damage?

 

There is no obvious damage to the wire connector on the top left of the rad. It's dark here now so I will check closer tomorrow. If I unplug this connector and apply 12v will this check the fan(s) for operation ?

 

This car has an auto climate control system. The compressor should engage 90% of the time to keep the windows from fogging. That's assuming you leave it in the AUTO position 90% of the time. The only other switch I use is defroster and even then, the compressor is engaged. IMO running the temp display up in winter and down in summer only causes blend door servos to fail prematurely. All 3 of my current cars have auto climate controls. All 3 are set to 75 all year long and are rarely changed one or two degrees. The fan for the compressor mainly keeps the systems head pressure stable not for controlling engine temperature.

 

Thanks! But just one is working :-(

 

Thanks! But I lost you since you said you have a POT...

 

Wait, so one fan is operating? Under what conditions and which one, left or right? Did it come on when you turned on the A/C? You will be able to see the fans if you pull yourself up in the driver's seat and look over the dash into the engine bay while the hood is open, then press the A/C button, and see which one starts to rotate; it should be the left.

 

Sorry, I just realized that this post consists of two separate problems from two different forum members, and at this point I am unsure of which problem I have been attempting to address since in my head I had combined all symptoms not realizing until just now, that they are from different poster's.

 

I am not the original poster with only one fan working ☺ i was concerned that I had never ever seen or heard either of my fans move. So today it hit 16c ; I drove the car for about 20 mins (about 5 at 100+ kph in 4th gear). Then I spent about 10 minutes in stop and go traffic. I got home popped the bonnet and turned the a/c on high and sure enough the fans started to run. I left the car idling with the a/c at the lowest possible temp and the fans gradually increased speed.....so it seems that all is well...and that I was just not observant enough

 

ok, I did what you said. When I turn the ac on, the right one start working. The left one never works. Any clue?

 

OK; please re-confirm which fan is operating, and confirm that the left fan or driver's side fan, is not spinning at all by itself by physically checking. Is that your right fan, or passenger side fan, as you sit in the car facing forward towards the fans? It should be the left fan or driver's side fan, as you face the engine bay sitting in the driver's seat that starts when you hit the A/C button after a COLD ONLY start. If there is a problem with the left fan, then the right fan may be kicking in off the bat to compensate although I do not know why it would not throw a code of some kind from this, or turn on the check engine light, something.

Unless something changed between 2003 and 2006 in the way the fans operate, then from what I have experienced on my car is that the left should be first to come on. Even when I do not run the A/C in my car, the left fan, or driver's side fan, always spins before the right fan or passenger side fan at some speed, and if it is really hot out, the left is already running, and the right will quickly match speed, and both will increase speed when up to temperature, and at a stoplight or idling etc., and the right fan or passenger side fan will cycle off and on, but the left fan, driver's side, will always be running after driving and reaching operating temperature.

I always wait until the right fan slows down and stops spinning after driving hard, or if it happens to be running when I pull into the drive, as it has never taken more than ~2 minutes for it to slow down and stop, the right fan that is or passenger side fan. The left fan is still operating albeit very slowly, and with no sound or vibration at all to indicate that it is running, and I have had to get out of my car and get my face down next to the left driver's side fan to confirm that it is even running, because at certain speeds it is very hard or impossible to see if the blades are spinning. I have also laid my fingers LIGHTLY on the driver's side fan blades going with the direction of spin to confirm the blades are turning on the driver's side or left fan, because as I have stated it is difficult to see it rotating under certain circumstances, and usually operates at a very low speed. When the right fan engages, or passengers side fan, is when the fan operation is detectable by the sound it makes at speed.

Please confirm the left driver's side fan is not running at all physically when the car is cold and before the A/C is turned on, hood and door open so you can get out quickly and check it for operation, then turn on the A/C and re-check to see which one comes on, driver's side or passenger side.

It could be that you have not driven enough to have it turn on to the point that it's operation is detectable, it is 'Variable Speed' and I have to open the door and put my hand under the side of my car to see if I can feel heat being pushed out of the engine bay to know if my passenger side fan is running or not at times. I did not think the fans were operating at all when I first bought my car, because I could not catch them in the act so to speak. A loose reservoir cap revealed that my fans were operating as intended, as both would be running loud enough to hear, while I pulled into my driveway to park, by the time I got back from the corner store.