90 XJ40/XJ6. The HVAC has worked great on the car since I got it. Ice cold A/C, toasty heat, and all flaps doing what they are supposed to.

But recently I am having difficulty changing temperature. Typically when I first get in to the car and start it, I can select any temp, and the system will respond correctly, but once we are up and running, it won't change anymore.

I have something in my head about cleaning the track for the temp control knob..... but I don't know if thats just wishful thinking on my part......

Any advice welcomed. It's a strange fault because when it does allow you to set the temp, everything is perfect, which is what is drawing me towards the control knob itself......

 

Sarc, I have a follow-up quetion to yours, I am still trying to figure out how the control panel works (1993 XJ6) the only positive control I have is "demister", the rest is Manual, Recirc, and then blue and white arrow slider. Must be a british thing because I for a life of me can't figure out how to get air to the legs.

 

Don't feel alone Mad Russian I have a 1994 XJ6 and still don't know how those controls work. I hope someone out there can help us both.

 

If the system is working right..... there is an auto and a manual button (on mine anyway). With the auto button you should be able to set the temp and let it go. My A/c doesn't work, so i keep it on manual or it will blast away and not get anywhere. There is a blow-up of the heater box somewhere around here. Don B pointed it out in another thread. Maybe he will show up. The heater box has cylindrical "flaps" that are run by small motors to direct the air flow. Its possible maybe one of the motors has gone south? Also there are 2 blowers and the system is set up so that both must be working for proper airflow. Not sure how helpful this is, but good luck.

 

Personally I'm not a fan of auto climate control its never warm enough or cool enough so 90% of the time its on max cool, max heat and I control temp using fan speed. I don't think mine works 100% but what I've discovered in my 94 is this..




From left to right - Fan speed dial is...Fan speed dial and Defrost will send it to defrost on high speed.

The 6 buttons are kind of self explanatory (I think)

The defrost button should turn on the compressor and open air to the windshield but at whatever fan speed your set at vs Max on the fan switch.

Demist should do the same but without the a/c compressor being turned on.

Recirc = Recirc closing the outside vent door

MAX = Overides the temp swith and runs the a/c at max

Manual = Overides the Auto A/C

The slider....Does really nothing as far as I can tell. From what I've read is that Jaguar "Does not wish to assault is occupants with hot or cold air but gently warms or cools the vehicle"

That being said this should control the amount of airflow from the upper and lower registers with the middle being 50-50. So if the upper vents are open it should get some air from both...

In my car the Vacuum doors are bad so this split doesn't work correctly. In the winter I usually just close the vents and allow all the air to go to the floor and in the summer with the A/C I open them and have a hose holding the vacuum doors open and it seems about 80% flows from the dash vents.