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The AC in my 1977/1989 V12 worked some years ago. I’m not sure it was working 100% as supposed, but I had cooling and AC compressor clutch switching on/off.
System is now again tight and recharged, and the blown inline fuse at the aux fan is replaced. Air is cold, so that works, but:
I do now have AC clutch and aux fan activated as soon as ignition is on, and they do not cycle on/off no matter what I do.
I have tried the following to see if I could find the relay/switch powering one or both units:
All positions of right AC control knob tried, including off.
Thermo switch on coolant pump disconnected.
2 relays behind radiator disconnected one by one
2 relays near starter relay (right rear corner of engine bay) disconnected one by one.
AC control unit in LH foot well disconnected. I also tried to connect the original control instead of the current modern control.
All of this with zero effect.
The black wire to the clutch is connected to ground, but still comes through bulkhead at right rear corner.
The orange wire to the clutch connects to a green/brown wire in right front corner of engine bay. This wire is hard to trace further inside the loom, but seems to go to the start relay area
One wire from fan is connected directly to ground. The other goes via an inline fuse to a black/green wire going into the loom at front right corner of engine bay.
According to my ROM the fan relay should be on the valence behind radiator. It's not one of the 2 relays placed there. I checked if one of them is for the horn, just for fun. That's also not the case...
It would not be too hard to add 2 relays and 2 switches to manually control fan and compressor, but it would be more fun to have it working as intended,,,
Last edited by leo_denmark; Aug 1, 2022 at 12:54 PM.
Reason: Adding a few more details
Well, I have both items on my wiring diagram in my ROM, but things are not close to being connected as shown there.
Clutch is supposed to have ground directly on one wire, while the other shall go to the AC thermostat placed on RH side of the Delanair. I still haven’t looked for the AC thermostat, but I should be able to recreate this setup.
Fan shall be controlled by a relay, which I have not found where it’s supposed to be. The relay shall be controlled by the thermostat switch on coolant pump and another wire marked 139 in diagram. 139 is according to the item list ‘Air conditioning/heater (to)’, which I have not found in the diagram or component location illustrations.
I could do a aux fan control update as described in other threads to make that work, but I guess I still need to find out where to pull a signal from the AC controls to fan relays.
Leo
Your car has the Delainair II, so I think the HE version of the D II is identical to yours. It sounds to me like the D II itself is swithcing on the f compressor, and the fan is comin gon because it is wired to do so if the compressor is activated. So solve the compressor and you solve the fan.
There is a guy on the Series III forum who had similar issues and it would be worth reading his diagnosis and repair story: https://www.jaguarforums.com/forum/x...ations-216854/
One question: ignition on, if you switch the entire HVAC system to off using the RHS cabin switch, does the aircon and fan still come on?
One question: ignition on, if you switch the entire HVAC system to off using the RHS cabin switch, does the aircon and fan still come on?
Yes, clutch and fan activates as soon as key is turned one click, also with the RH knob in OFF position. This knob has a cam activating 4 micro switches, I hope they are not giving up…
Thanks for the input, I will check out the other post.
Yes, clutch and fan activates as soon as key is turned one click, also with the RH knob in OFF position. This knob has a cam activating 4 micro switches, I hope they are not giving up…
Thanks for the input, I will check out the other post.
Leo
I think they are leo! But the guy in the link sorted out a problem with this exact switch, so I think you have help at hand.
I have now been through the linked thread, and it was nice reading. As one of the comments said: Very methodical! The engineer in me is suitably impressed.
I think you're right about that the microswitches at RH knob is under suspicion.
Yesterday I didn't have much time, but I did try turning LH knob from low to high temp just to see if controls not calling for cooling would make a difference. That was not the case though....
I attach the 79-80 wiring diagram I use. Credit for the colorizing goes to Paul Kobres (from FB groups)
...I need to take a good deep breath before diving in. Will probably become a winter job
Good idea!
I took the entire winter of 2018-2019 to make my system work correctly, couldn't drive the car anyway, and I'm glad I did. (I have adjusted, repaired or replaced every component aft the firewall except the evaporator. That includes both fans)
Once you have it sorted out you won't need to fiddle with it again for 40 years!
(';')
All back together again. It turned out the swiches worked fine. I still changed to ned 'new' set just in case there was a problem when loaded with a switch.
If the mounting screws were tigthened without pushing the switches towards the cam, the swithes was not switching. I decided to make the mounting holes slightly oblong to make it possible to push switches a bit closer to the cam.
Function was checked before assembly, all was good.
The not-so-good part is that nothing has changed, but at least working on the car keeps me away from the pub...
Ventilation fans are running in off position (slow)
A/C clutch and fan turns on as soon as ignition is on, also in off position
No heat. I checked the water valve, it opens.
What I have not checked (lately) is water temp sensor resistance and the 4 relay pack function, so that's on my todo list.
AC control blues
