It can wait until whenever you decide you want cold air conditioning!

I don't think a 92 has airbags does it? That makes it easier. I have pulled the dash on mine and I think I had it out in ~2 hours? I have airbags, so I had to make a special tool for disarming the drivers side bag, the passengers side is able to be disarmed without any special tools.

Doing a dash isn't as hard as you think. The manual is good, remove the bolts (maybe 10 of them?) and out it comes. Radio has to come out, that may or may not be tricky depending on what it is. Speedometer cluster and trip computer too, but that's not hard.

Here is a video of an A6 compressor running:
You can see the clutch cycling the compressor in and out. It's an electromagnet clutch, it just pulls the clutch plate together when it needs to engage the compressor. The wires for the clutch are at the 10 o'clock position when looking at the nose. They are usually at 10 or 2 o'clock, there were many cars that used this basic design, so there are variants.

So if I understand you, the muffler (3) creates gas from any liquid using engine heat, said gas is then sent along hose (5) to the compressor. That makes sense - the leak appeared to be gaseous in nature, due to the way it blew bubbles through the oily coating.
So the route is from there to the compressor, from the compressor to the smaller black cylinder, then out via (7) to the condenser where it's turned into liquid again I assume, then I guess it goes out from Reciever-Drier along hose (1) back to the a/c unit. Or I'm probably wrong....

I'll take another look at the intake manifold and see if I can't spot a fuel cooler or similar.

My car's a Japan-market car, originally sold by Jaguar Japan - it has the Exhaust Temp Warning light that's Japan-specific, for example, and the VIN is the Japan-market VIN, so definitely not a parallel import.

You are correct. The compressor takes a low pressure gas and turns it into a high pressure gas. It then goes through the condenser, which is like a radiator in front of the cooling system radiator. That sheds the heat that was picked up inside the car, and from the heat of compression. The high pressure gas condenses into a high pressure liquid as it is cooled. The receiver dryer is a metal tube above the radiator cross member and it removes any water from the refrigerant. There is a decessant bag inside the dryer.

Refrigerant then flows through the small metal pipe (1) to the evaporator inside the car. This also looks like a radiator and here the refrigerant goes through the expansion valve, where the pressure is released. Think of it like a small orifice, although there are different types of metering/expansion valves. This causes another change of state from liquid to gas as the refrigerant expands. Ideally, the entire evaporator is full of boiling refrigerant, but no liquid carries over to the compressor suction line (5). Of course to boil a liquid requires heat, and that heat comes from the cabin air that is blown across it by the AC system fans inside the car. Once the heat is given to the refrigerant it exits the evaporator and returns to the compressor for the cycle to repeat. The muffler (3) is positioned fairly close to the exhaust to make sure that any liquid that escapes the evaporator is boiled off. It's insurance to make sure the compressor isn't damaged by sucking in any liquid.

If your refrigerant is low, then it may only half fill the evaporator with boiling liquid, and the ability to carry away heat is limited. Over fill it and you have liquid carry over into the compressor which can damage it, and the refrigerant can't fully expand, so it's ability to carry heat is also limited. The AC system will always say how much refrigerant is needed, and that's why. Too much or too little is not good.

Wow. That last post should be stickied. Indeed, when I touched the muffler it was quite hot, and I was wondering if it should be that hot. Apparently yes, so that's good.
The video was also very informative - now I know where to look and what to look at.

My '92 has a driver's airbag in the steering wheel. I've read other comments that say dash-off jobs are the worst, but if it's not that bad, it might be worth tackling after all. My usual garage was fairly coy with any actual figures, though admittedly I didn't push the issue too much. The first major issue to tackle is probably the engine vibrations at idle, which aren't that serious really in terms of how it affects the car, and appear to be due to old mounts. The garage said that would be expensive as they have to lift the engine. I came back at them later saying the apparently the subframe only had to be lowered, and the guy still said it was expensive, giving the impression it was what was intended all along.

Anyway, I'm waffling. Thanks again for all that very useful info and advice - very much appreciated.

The V12 isn't actually perfectly smooth at idle, it's more pronounced with the later HE versions after 1982. Is the vibration only at idle? Under load? Under all conditions?

Changing motor mounts is indeed tricky, but with so low KM I'm really surprised it would need doing. They are not a usual failure point. Can you make a video and post it on youtube showing the shake?

Only at idle, yes. It seems to be slightly improved after new spark plugs, for what it's worth. It's mainly felt at the lights - every so often I'll feel a mild shaking or vibration through the seat. It seems to be more pronounced when the engine is warm, which to my non-expert mind suggests the rubber mounts are more flexible, but then again harder mounts should make the problem worse, not better. So what do I know?

I'll get a video up as soon as I can. I'll take her out today and take my video camera as well.
I've seen a video of an Australian review/test drive of a V12 XJS where they could balance a coin on its edge on the fuel rail.

Do you feel it in the small of your back? Bit of a thump? I suspect misfire, so I would be looking at coils, wires or plugs. There is a diagram (somewhere) showing the routing of the wires so they make as little contact with each other as possible. It is possible to get "crosstalk" between them, where one wire can trigger another to fire at the same time, sort of inductance between them.

Do you know what kind of plugs were put in? I believe Jaguar recommends NGK BR7EF - but I'd need to double check. I think it's in the owners manual.

More in the butt, in the seat. It could be a misfire - there was a TSB showing an issue with rough idling and suggesting new wires and showing their ideal routing - and when the shop changed one wire (which apparently was contacting the metal by the compressor and causing a misfire - at one point the engine shaking got quite bad so that was when all plugs were changed and a new wire added) but the wire was one they had in the shop and modified. A new wiring set would definitely be cheaper....

I'll see if the repair docket says what type of plugs were used. I did ask and they said they were the standard sort for Jags.

Several of the vacuum servo operated flaps use restrictor in the line to dampen the flap movement, it is possible the flap in question is OK and simply needs the restrictor replaced. These can be accessed by removing the forward console extensions by removing the 2 screws holding the footwell vents. The closing of that vent when turned off sounds normal other than the speed of movement.

Thanks. I've already taken that panel off for another reason, a while back, so I should be easily able to do it again. What would a restrictor look like? I can take a pic of one side if that makes it easier.

restrictor looks like a small squat cylinder about the size of a small coin but thicker with tube in and out. There were several colors used to distinguish different rates of restriction (3 and 4 in pic)

Cool. I'll take a look. Many thanks.

I had a poke around under there, and could only find wiring. A lot of wiring. Plus some large bright blue softish plastic things at the back. So I'm not sure what I'm supposed to be looking at.
The first photo is the side panel under the passenger knee area removed, showing wiring and the a/c duct.
https://cimg2.ibsrv.net/gimg/www.jag...1c14a0c821.jpg
The second photo is above that, with the knee bolster undone and moved out of the way.
https://cimg8.ibsrv.net/gimg/www.jag...030fc2e39f.jpg
The third photo is aimed more towards the engine/firewall, with the fuses visible and the large blue things at the back that might be a/c-related.
https://cimg7.ibsrv.net/gimg/www.jag...e92f9842b8.jpg
It's very hard to peer behind all that wiring, however. I only tried the passenger side (left) so it might be easier to see from the driver's side. Perhaps.
Am I missing something, or looking in entirely the wrong place?

Jagboi - here's the video on YouTube. I wasn't sure how to make the vibrations clear, so used the Jurassic Park trick of a glass of water. Of course there's always going to be vibrations, but I think it's actually easier to see by how the camera moves. It's not serious, and definitely does seem better with new plugs and/or with that replaced wire, as in I don't notice it every time I'm stopped, but every so often it does make itself quite noticeable.


I couldn't find anything that looks like a fuel cooler. The hose just sweeps around in a single flow, and there doesn't appear to be any connection to anything on the intake manifold and the a/c system, as far as I can see. I assume it's there somewhere, however.
https://cimg5.ibsrv.net/gimg/www.jag...0ba0e6af64.jpg

For reference, here's a pic of my wires and the one the garage added.
https://cimg6.ibsrv.net/gimg/www.jag...ddef6d6bb7.jpg
(It also shows the successfully adjusted cruise control actuator rod.)

The black duct in your pics is pretty easy to remove, just remove the single screw centre bottom flange and the duct can be tilted slightly to disengage from the tab on top flange. With that out of the way you will see solenoids and restrictors. If the only problem with it is the noise it makes on occasion l would be tempted just to live with it, it won't hurt anything.

Ah, behind the duct. Yeah, the actual operation itself seems to be fine - though there is a slight bit of warm air from the left side of the dash vent even when the system is off, which fogs up that part of the windscreen on colder days. But switching the system on to Demist gets rid of it in a few seconds, so it's not a major issue.

Doesn't seem to be big vibrations, but if it comes and goes it could be a misfire. As a thought, the distributor cap is usually aluminium terminals inside, and they can corrode. Give each plug wire boot a few twists back and forth to move them a bit and expose fresh metal. See if it makes any difference. I'd do the same at the plug ends and make sure the wires are firmly seated on the plug.

You might want to try new coils and a plug wire set. Can rockauto.com ship to Japan? It's the cheapest place I have found to buy parts. I know they ship to the UK and the prices were reasonable. I chose the economy consolidated and it went airfreight in a few days it was there. Assuming you have a few sockets/spanners are are willing to get your hands a bit dirty.

I'm thinking if one wire has gone bad, others might not be far behind...

Thanks - I'll try twisting them. Rockauto says they ship worldwide.
...And I have just successfully ordered some wires. I chose "Premium/Better than OE" and selected these:
More Information for BECK/ARNLEY 1756112
"EPDM inner insulation prevents arcing and voltage leak."

Shipping actually costs more than the wires.... These definitely fit OE, with the alternative LNA1509AA part number that is the new Jaguar style, and claim to come with clips. I might even be able to fit these myself, though not after getting more advice...
Thanks again!