Guys
XJS forum interloper here again! I have a friend with a series III V12 XJ saloon 1989 model. There is no 12 volt feed to the compressor. I have downloaded the manual that Doug put up about 2 years ago, and that says pin 20 on the "grand piano" aircon ECU is what should trigger the feed to the compressor rely.
There is a fuse in line to the relay. I know how to change the fuse (once I have found it!) and also test the relay (ditto), and anyone who can help with locating these, please post ASAP. Additionally, can anyone tell me how I test the pin 20 output on the aircon ECU? Somehow I have to test it when it is plugged into the loom plug, and I do not know how, or even how to find pin 20.
Any other help anyone can give me about the Delanair III system system as a whole would be greatly appreciated.
Greg

 

the fuse Doug might have referred to, must be located on the side where the Servo and flap linkages are.

you need to remove the two screws of the black plastic floor Vent, then pull the upholstery panel towards the firewall to release two "L" clips from the front side of the center console.

then you can see the flap linkages. The servo is normally covered with a black plastic cover and it sits on the transmission tunnel.

the fuse will be in a white fuse holder held on a "C" clip, up towards the rear of the Servo and linkages, very close to the firewall.

Since the Delanair 3 is slightly different from the Delanair 2, I am only guessing, I have no experience with the Delanair 3, only with the Delanair 2. I hope this helps to find the fuse.

 

The Delanair manual makes reference to a Thermal Fuse. Is that what you are wondering about? If so, strike it from your list. An '89 won't have it.


Look for the green/brown wire. That'll be pin 20

I recall that the connector to the grand piano allows for back-probing of the terminals, if your meter probe is is pointy enough

Corroded connectors and grounds can be a problem. I've fixed a couple D III systems just by cleaning them. Some of wiring (and connectors) is quite tiny so even a little corrosion is a problem

Cheers
DD

 

Doug
Thanks for the wire colours. I am sure I read somewhere that there is an inline fuse after the pin 20 outlet before the relay. I read the first para on page 8 of the manual, which lists checks for the compressor not engaging. Line one says; "check fuse adjacent to starter relay at RH corner of engine bay, 10 amp in line."

 

Doug, I found this, see post 8
https://www.jaguarforums.com/forum/x...ration-111037/

 

Which might help you find the compressor relay.....if indeed one was used on the Series III. Look for a GN wire with an inline fuse and follow it along. Such a fuse might be in the cabin, not the engine bay.

Cheers
DD

 

Guys
Today's news on the Delainair mark III:
I went over to Monsieur di Benedetto's workshop and there was an absolutely PRISTINE V12 XJ mark III Saloon in Solent Blue. No rust, it could have come out of the factory yesterday.
Armed with the manuals and diagrams Doug, JJJ and Grant and others kindly provided, we did some tests.

1. There was voltage to the compressor (testing with ignition on, mode switch to Defrost to over-ride the warm-up phase before which the system will not start). Thus no worries about the ECU, relay or fuse.
2. The earth from the compressor is a loom wire that disappears down the V to the firewall somewhere. This earth was not capable of transmitting a high enough voltage to engage the compressor clutch, barely managing 10 volts.
3. We ran an extra earth from the compressor to the rad panel and voila! all working.

Many many thanks again for all who helped. I explained to my friend that the finest Jaguar XJS and XJS Series III experts from three continents (London, Paris, New York, Seattle, Adelaide, Texas etc etc) had contributed over the weekend to my new-found knowledge of the Delanair III and he was suitably impressed.