Low vent heating problem:(
 

Hello, I am new here,but I am really counting on your assistance. I own a beautiful Daimler Double Six 1991 with one but really annoying problem: when the climate control is set to Auto, even at the extreme cooling temp.like 65F, the lower(foot) vent blows hot air, the upper vents blow the right cool temperature air though. Now a funny thing: when switched to the MANUAL climate control mode and set for the extreme freezing of 65F(and that temperature only),the lower vent blows really freezing air. When (still being in the MANUAL mode) I turn the temperature towards warming (any higher than 65F),the low vent starts blowing hot air again. Other vents seem to work just fine. So my dream car,basically driven in the summer time,puts me in a funny situation: I can eather get totally frozen, or my legs get fried ;)
Anyone of you,Jag fans,have any idea what causes the problem? ( my mechanican does not)

are the climate controls in your 1991 Daimler Double Six similar to the Jaguar XJ-6/12 (1980-1992) climate controls?

post a picture of the controls to confirm.

Yes,the Daimler is,except for some details,just a regular XJ12,the climate controls are exactly the same as in XJ6/12s.

thanks for confirming. I am assuming it is a Delanaire MK-2 system. But I've never seen this symptom in my XJ-6. I can only guess the problem is at the Mode Switch itself, or at the SERVO located behind the mode switch.

take a look at the attached PDF file to learn about all the parts involved in the switching between a/c and heater and vents. I wished I could offer better help but this one has me puzzled.

Jose,thank you for your help, I will keep searching for the solution :)

you welcome! here's a Delanaire MK-2 and MK-3 Service Manual with troubleshooting steps.

You'll want to use the "Mark III" sections of the service manual that Jose provided.

The Ser III 12 cylinder sedans went to the Delanair Mk III system in August 1986. Prior to that they used the Delanair Mk II system.

The Ser III 6 cylinder sedans used the Delanair Mk II system right up until the end in April 1987.


Cheers
DD

I would suggest spending a couple hours very thoroughly cleaning all the tiny connections relating to the climate control system. There are 3 or 4 on each side of the climate control case behind the dash....a couple of them up quite high and hard to reach. These are easily recognizable because of their small size and the small wire size. The tiny pins inside the connectors often corrode.

Also find and clean the two main grounds for the system. You should see the ground points on the vertical dashboard braces on either side of the main climate control case.

I have fixed two misbehaving systems by simply cleaning the grouns and connections. You might get lucky as well. In any case, the possibly of poor connections needs to be eliminated before more in-depth testing takes place

Cheers
DD

Thanks Doug, now I see why I haven't experienced that symptom before, since I've never dealt with a MK-III Delanaire system.

Thank you Doug, I will let you know if it solves the problem.
Greetings from the beach of the Baltic Sea!
Chris