Team
I have a 1988 XJS with Improperly working air doors. When I have the A/C on everything blows out on the floor. When I turn on the defrost some of the air comes out from the windshield. I really don’t want to take this dash apart. Where would you start looking? Vacuum leak under the hood or a bad amplifier?
Please advise.
Thank you!
Better question… what wires would I need from the amplifier to hot wire and activate the servo. If the servo turns on and the air doors close properly I probably have a bad amplifier.
Search back a little and you’ll find a few recent threads on the A/C and heater control systems. Someone posted the Jaguar diagnostic process you should follow to figure out what the problem is.
Brian,
Does your 1988 XJ-S have the Delanair MK II or MK III climate control system? One quick way to tell is the temperature control knob in the MK III has a a manual control position if you pull it out.
If your heat and air conditioning modes both work and seem to control temperatures properly then your door problems might be in the vacuum control system and not the amplifier.
Climate control problems are discussed regularly on this list. Member Lockheed1 posted some very helpful information with good Delanair attachments recently. You should check the archives for his posts and many others over the past month or so.
Have you owned this car for a while now and your normally functioning system started to act up? Or did you recently acquire this car and you are trying to sort it out?
Paul
Thank you for pointing me in the right direction. There are so many posts about topics on this site that my head spins trying to find what I am looking for. After looking at the system it appears to be a type III with the knob that pulls out. When I pull the know and play with the temperature nothing happens with the air doors and it all still blows out all over the floor. Ill look around and see what I can find.
Thank you!
Brian,
I had the same problem with my 91 XJS with the MkIII system. Turned out to be a broken vacuum “T” fitting resulting in no vacuum to operate the center dash air flap. The “T” fitting is underneath the Delanair unit behind the radio, so not too difficult to access. In any case, look for vacuum leaks or absence of vacuum coming from the engine.
Cheers, Richard
Brian,
It is good that your car has the later Delanair MK III system because it is not plagued by the A/C amplifier (C45402) problems that the MK II system had. I am not sure when the MK III replaced the MK II in the mid 1980s. It is likely that you have a broken vacuum hose or fitting and not an electrical issue. This is especially true if someone has been inside the dash for any reason, like to replace the OEM radio with an aftermarket one, because that is the area where the vacuum lines run.
Paul
Thank you… You know the old radios were much shorter than the newer style ones. You get some kid installing it and its like putting 10 lbs of crap in a 5 lbs bag. They probably stuffed the radio in there and broke something. Sadly this is why you have to do everything yourself. Hope I can get it apart without busting something!
So after opening everything up, the vacuum line to the center air door had fallen off. On top of it this bundle of wiring was wedged between the re-circulation air door. Now I have some volume coming from the center air door, I still have some volume coming out on the floor by my feet. I took the servo off and tried turning it manually between 9 and 3 oclock but no matter what I do I cant get the center vent to blow without air coming out at my feet. The only time this stops is when I put the defrost on. Any ideas?
!My '88 Delanair 3 behaves exactly as you describe, and I think you’ll find that is the way it is supposed to act. When I ask for A/C the center vent will open, plus the side face-level vents, and also the floor vents. If I go to defrost, the system goes to heat, and only the windshield gets airflow. Perfectly normal IMHO.
Ok… thats what I wanted to hear. I’m not going to fiddle with it any more. Its a buddies car that lives in LA. He bought a DB9 and is tired of paying for 2 parking spaces in his building. I’m going to sell it for him, but I don’t want to sell something that’s not working properly. Thank you for responding to this!
Brian.
