I have a Jaguar S Type SE 2.5 Automatic 2004 57000 miles
Problem started 2 years ago. I Always set climate control to 20°C Summer or Winter. Then found I had no hot air until I increased the temp to 22°C. The next winter had to increase this to 24°C now the setting is at 26°C before I get any heating out of the system. Whether the Air Con is on or not makes no difference. Below this set point air temp from vents is at around 8 -12°C. but as soon as I change the setting to 26°C vent air temp shoots up to over 30°C.
Cleaned the Temp sensor in dashboard with no noticeable effect. Once the Climate control is now set at 26°C everything works OK.
Any suggestions what could be the problem?
Thanks
Brian

Does ext temp reading (in LCD panel) match actual?

I think there are 3 temp sensors at least - see previous threads / JTIS.

I only thought there was one sensor in the cabin. Can you tell me where the others are located.
The ext temp reading in the LCD panel matches the actual external temp within 1°C

If you are getting into your car this deep get the right stuff!!

The JTIS and the JEPC are both free on this site. The JEPC is the parts catalog and the JTIS is the shop manual. Both are factory documents and are very useful but I have seen way better repair books!
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This sounds like a typical DCCV to me.

Hello i have had the same issue and this is a common problem. The heater valve situated at the front left of the engine under the water expansion bottle become defective which in turn messes up the cars heating cooling of the A/C this part is around £80 brand new and there are different types depending on the model and age of the car. This is the most likely issue not the sensors in the cabin which yes there are 3 I believe 2 on the passenger side and one on the drivers side in and around the foot well and glove box area . The only other major reason is the duel climate control module can burn out as a result of a faulty heater valve these are expensive even second hand but if you can solder its an easy fix. First remove the glove box and look for the climate control module. Unplug it and take it apart and look for any burnt tracks on the circuit board this is easy to spot. If this is burnt then your problem definatly lies with the heater valve which will need replacing and the CCM repairing. If you are lucky your CCM will be in perfect condition then just replace the heater valve. If these both do not work then look at sensors. Below is a link for a heater valve and description on ebay.
http://www.ebay.co.uk/itm/181397460831?cmd=VIDESC

If i had you address i could post you a CD i no longer need which is a manual that shows you how to remove and install the whole car or you can just buy one for under £5 on Ebay

http://www.ebay.co.uk/itm/261364442912?_trksid=p2059210.m2749.l2649&ssPageNa me=STRK%3AMEBIDX%3AIT