Hi
I know Boomer is having heat system issues with his Jaguar and there are probably many other forum members (including myself) that are having related heating issues.

I put together all of the description and operation information in these PDF files:

Climate Control Components (section 412-04)
2001 XJ Climate Control Components.pdf

Heating and Ventilation (section 412-02)
2001 Jag XJ Heating & Vent Description.pdf

Air Distribution and Filtering (section 412-01)
2001 XJ Air Disbribution & Filtering.pdf

Air Conditioning System - Description and Operations (Section 412-03)
2001 Jag XJ Air Conditioning Description.pdf

Maybe if we know where all the bits and pieces are located and how they function, we have a chance to solve some of these issues.

We have some expert Jaguar Techs here on the forum who probably can point out some of the parts that might need our attention.

Jim Lombardi

 

Thanks, Jim.

It's too bad Jaguar doesn't go in for detailed diagnostics or troubleshooting. Perhaps they think CEL codes are all you need. But I don't know if any are generated that pertain to the heater or AC. My problems haven't set any codes (that I can tell) so I suppose it will have to be a trial and error process. But it's now snowing outside, so I have a couple of months to think things over before I touch the car.

I have been looking in the JTIS for such information as there is. One frustrating thing about that document is that there isn't a good "go back" feature. I often have to start over at the beginning and work my way down the info trees.

 

Hi
I am only getting heat when I use the climate control for the lower air duct (feet) or the other one for the facia air duct. The Automatic control - no heat and combination Facia/Feet control- no heat; both are just giving a little bit of cold air.

Hoping to solve heating issues by doing all this documentation.

I just want to add some of the JEPC (Jaguar Electronic Parts Catalog) sections that pertain to the Heating and Air Conditioning information.

Here are 4 JPEC files that show:
Water Valve, Water Pump and Hoses (that the Heating & Air Conditioning systems use)




The Air Ducts - these 3 sections I copied from the JEPC







The Footwell Air Ducts below give part numbers for both LHD (Left Hand Drive) and RHD (Right Hand Drive) Jaguars



Jim Lombardi

 

Hi
Here is a page I extracted from the Air Duct PDF file and created this JPEG file that shows a nice overall summary of the heating/cooling duct system:



Jim Lombardi

 

Jim -
Is it just the "automatic" setting that is not working? If so, that would imply that either:
1) the Automatic button itself was not sending out the correct output (I don't know what pushing it does, electrically) or
2) the wiring between the Automatic button and the climate control module has a short or open (dirty connector?) or
3) the climate control module itself is faulty.

Did the Automatic mode work OK during the air conditioning season? If so, it might turn the diagnosis more towards the module.

 

Hi Boomer
The funny thing is that all the climate controls works fawlessly when operating the air conditioner.

Jim Lombardi

 

Maybe **really cold weather** is beyond the "parameter space" (to use an engineering phrase) for British engineering!

But seriously, I guess if I had your problems I would first clean and reseat all the connectors to the control panel, and then to the module. Then I would buy another module and try that. Maybe eventually I would build a bonfire out of the car, to stay warm! (or maybe not drive the car till Spring)

 

Hi
The Climate Control module also stores Fault Codes about the Heating & Air Conditioning components.

Here is a JPEG I made from the JTIS21 page on it:



The AUTO mentioned above is the button for Automatic control of the system.

The RECIRC is the button for the recirclation.
The FACE is the button to turn on the upper vents (pointing to the person's head).
The R is the button for the Rear defroster (Heated Rear Screen).
The FAN is the Fan Speed button.

Here are the images of the Climate Control buttons mentioned above:




The Climate Control Fault DTC are listed along with the diagnostic instructions information I extracted from the JTIS21 and put in this PDF file:

2001 XJ Climate Control Fault Codes.pdf

I noticed that I had a fault code 14 stored in the Climate Control module.
A fault code 14 is a water temperature input malfunction - possibly caused by the output from the instrument cluster module.

Apparently this is a leftover fault that was caused by the instrument cluster module we had to replace a month ago. The circuit board in the instrument cluster module was bad.

I cleared the code 14 using the information in the JPEG above.

Jim Lombardi

 

Thanks, this is FAQ worthy

 

Jim -
I'm losing a bit of the story here.... Are you saying that you cleared the "code 14," and that doing so made problem(s) go away, and now your heater works fine?

 

Thanks, I had a P1638 fault, and after a hard reset I ended up with a ER message on the A/C with a "ding". I found out a had a code 11, and 44, got rid of them and A/C is fine now. I could have never figured this out. Inst. Cluster Panel is being rebuilt. Thanks, Thanks , Thanks. Ron (98 XK8 100K miles)

 

How difficult is it to replace the heater water pump on a 1998 xj8? How long should it take? Boy, this is one expensive part.

Jagpg

 

Following the instructions for the actuator test below, a couple of questions:


Will the test repeatedly cycle itself until interrupted?
Mine appeared to do so, until I interrupted it with the fan button.


How do I interpret the results of the actuator test?
I did the procedure over again, only to check for codes, and there were no codes stored- it gave me "0".

 

I wouldn't have been able to sleep well if it hadn't been for your post. Got my er code cleared. Thought I was in for some real trouble but your post saved the day as it Did for hundreds if not thousands of others. Cheers.

 

jagpg, replacing the pump is not too bad. The location is certainly not the most access friendly and requires a little dexterity, but not impossible. I recall doing it in an hour or so. I also go back in that area every winter to flush/back flush the heater core. Originally thought my pump was at fault and replaced it, but turned out to be clogged heater core. Are you sure you heater pump is shot?