Tiny Air Leak in Hose Connector Above Compressor
 

Yes, it's me again with yet another noobie question. When I was pottering around the engine checking the vacuum tube to the cruise control, I noticed a tiny air leak coming from the metal joint where the thick hose that snakes around from the bulkhead to the a/c compressor runs across the compressor itself. The cruise control vacuum tube by the tie is coated in what appears to oil or lubricant.
If anyone knows what is leaking and how urgent it is to fix (it's the New Year holiday period from around now), I would be very grateful.
https://cimg2.ibsrv.net/gimg/www.jag...7d68558ab5.jpg
and
https://cimg4.ibsrv.net/gimg/www.jag...c3d8687794.jpg

try some dish detergent mixed with water in a pray bottle, turn on A/C and spray area, if it bubble then you have a leak

That would be refrigerant leak and air con oil. Leave a/c off and have it fixed when convenient.

Thanks. Does that also include leaving the heater off? I hope not, not in winter....

You have a refrigerant leak on the return side of your air conditioning system. The only solution is to degas, replace the hose, regas. Theer are products I understand that you can add to perhaps seal it, but they have a reputation for knackering other far more expensive components in the system. GREAT CARE must be taken when undoing the hose from the valve on the firewall, and the valve MUST be supported with a spanner against the undoing torque, it has special flats on it for this purpose.
Greg

Oh great. That sounds expensive, and definitely beyond my skills and equipment. I'll pass on your comments about the firewall valve hose when I get the garage to fix it.
Thanks for the advice, as always.

You can still get the hose from Jaguar I am pretty sure, or an aircon specialist will know a hose repairer; the flexible hose is special stuff as the actual molecules of the modern refrigerants worm their way out between the molecules of the old type hoses!
I think your model deleted the fuel cooler, this was in the aircon circuit between your leak and the valve. If you do have it, changing the hose is far simpler. It is a cylinder about 6 inches long by 1.5 inches fixed to the top back of the B bank air filter box. The leaking hose will terminate in a screw fixing there if you have it. A regas is not too expensive, and the time to fit a new hose not too long!
Greg

From memory, the long hose goes straight from the compressor to a brass cylindrical unit just ahead of the firewall. Yes, it's just like this diagram, with the hose being Part 5. It appears to be available for anything up to 100 quid or so. Or less for aftermarket.
https://cimg4.ibsrv.net/gimg/www.jag...c19334e8f8.png


Looking up the situation over here, it seems the best bet is to take the car to an automobile electrician - many garages will just subcontract it out to one anyway. There's one not far that says foreign cars are welcome (no doubt for an extra charge - this is very common over here). I'll try them after the New Year's break.

An automobile aircon specialist, rather than an electrician, your garage may have one on the staff, or may not.
Greg

The compressor will engage as soon as you turn the fan on whether you select heat or cold. You can simply unplug the feed wire to the compressor at the compressor or at the relay. That will immobilise the compressor but leave you with heat.

Greg: I'm pretty sure the garage isn't that big. I could always start with them I guess. From what I gather, automotive electricians in Japan are the people who deal with aircon. I can't find any reference to pure aircon specialists, but several sites that say that automotive electricians (rough translation of "densouya" 電装屋) deal in these things, as well as several densouya websites that mention their specialization in a/c and other electrical stuff in general.

Baxtor: Thanks. Is the feed wire reasonably easy to spot? I wouldn't want to unplug the wrong thing.

Easiest way to do it would be to start at the compressor clutch, locate the wires coming from that and follow back to the first connector you come to. Unplug and jobs done

Thanks again. Now for my next silly question. Where's the compressor clutch? I'm slowly starting to learn what the various things in the engine bay are, but it's a slow process....

The clutch is basically the pulley part. In your photo the feed and earth wires (I think) are in that plug just under the rubber part of the offending hose. Have you checked to see if you have the fuel cooler? If you have one it will be as in the attached pic.
Greg

The green, yellow and black wires that disappear into a hole a bit to the left of the metal clip around the fat hose?
No, no fuel cooler - mine's the system shown in the diagram I posted a bit earlier. One long hose.

A 92 will have a pressure switch on the compressor (earlier cars had a superheat switch), so no need to unplug anything. As the freon pressure drops the switch trips and the compressor clutch won't engage to protector the compressor.


Did you actually hear a leak there? I'd be very surprised if you did. The outside of the hoses is oily just from the environment of the engine bay. It happens.

First thing I'd do is test the AC and see if it works. Blowers to hi, temp to full cold and manual ( I think you pull the temp knob out to do that, and disengage automatic). engine running. Then put a thermometer in the vents and see what you get. If it's working you should be able to see the clutch at the front of the compressor (the black cylindrical device at the front of the engine) cycling on and off. It's the nose of the compressor, in front of the belt, it will turn when the clutch engages and stay still when it disengages. Even if the system is completely out of refrigerant you can still use the heater, it just won't have the dehumidification that it would with a working AC circuit.

AC work isn't difficult or magic, just needs a special few tools. Rather than a hose I would think that new O rings on the joints would be needed. It's hard to say what was done, as the car was originally built with R12 refrigerant, and now you can't get that, your system has been converted to R134a refrigerant. Who knows how well that conversion was done, or what was done; as there are shortcuts.

It's not difficult to make up new hoses, the fittings are all standard sizes. Nothing here is Jaguar specific. That hose goes over to the fuel cooler, not to the expansion valve on the firewall.

The compressor you have is a GM design called the A6, originally made in 1964 I think. It's a really tough, durable compressor, one of the few with an oil sump. Kind of power hungry, but works well.

The weakness of the way Jaguar used it is the hoses are held against O rings on the back of the compressor by a plate with a bolt though the middle that clamps the hose ends between the plate and the compressor body. Since it's a single bolt, if it's overtightened it bends the plate, and the hoses are no longer held parallel to the compressor body and they leak.

The other problem is the plate that Jaguar used is about half the thickness of the plate that GM used in the 60's and 70's, so it's much more likely to bend. The solution is to get a thicker plate and then the hoses will be held properly against the O rings.

Of course the system has to be depressurized and opened up to change the O rings, then a vacuum is pulled to see if the system is leak tight; if not then you start chasing leaks. Time consuming, but not difficult. If you plan to do any AC work it's worth it to buy the gauge set, hoses and a vacuum pump. They are not super expensive and soon pay for themselves if you're capable of doing the work. There are lots of AC forums that can help you, or people here have done it too.

Thanks very much for that very detailed reply.
Ah, nice to know I don't have to worry about unplugging the wrong thing.

Actually, I haven't heard any leaks at all. What happened was that I was tracing the vacuum hose for the cruise control to see if it appeared damaged or brittle, and noticed that right by where it's tied to the a/c hose it was covered in what appeared to be oil. On closer inspection, I saw a tiny (1mm) bubble appear and reappear right where the arrow is in my first photo. If it's got the potential to be serious, I want to catch it sooner rather than later....

The a/c itself appears to work fine (I haven't had the cold full on lately, but a few days ago it was warm and sunny and I did set it to coolish, and it worked fine). There's a vacuum issue I mentioned earlier on another thread, whereby turning it on results in a loud THWAP from about the middle of the dash as, I understand it, the sudden application of vacuum causes a flap to suddenly open or close - in other words, the system's not holding vacuum when it's off (there's a groan of vacuum releasing when it's turned off -esp. noticeable when the demist function is used). Other than that, it does appear to work, but I'll check the full cooling later today. And wipe the hose clean just to be neat....

There is a vacuum motor on the centre vent, it's open for AC, and closed otherwise to push hot air to the defrost and the floor vents. That may be what you are hearing. Or a vacuum line has come off under the dash somewhere.

Seeing bubbles like that is not normal, that's leaking refrigerant. That's the low pressure side of the system, but with the system off the pressure equalizes throughout. Eventually it will need to be fixed, that will be a new/rebuilt hose. Not sure about Japan, but there are AC and hydraulic shops here that can replicate existing hoses. The metal pipe going to the compressor isn't an off the shelf fitting, but they would reuse that along with new hose and put a new ferrule on the end and then crimp on the new hose to the old metal pipe. Or buy one from Jaguar if it's available.

Thanks again. Yes, I gather fixing that THWAP will basically be a dash-off job, which will be expensive. As the a/c works, it's not an urgent issue.

And yes, bubbles like that didn't seem normal to me, either. The places to get a/c repaired in Japan appear to be what I loosely translate as "automotive electricians," and I haven't found any reference to car a/c specialists as such. Your use of the word "eventually," however, suggests it's not an urgent issue, and can wait until next year.

Part #3 is a muffler. It's kind of an accumulator so that any liquid refrigerant coming out of the expansion valve (which is attached through O rings #2 and 4) will go into the muffler and be boiled off by engine heat into a vapour. The hose then goes to the suction side of the compressor. As liquids are incompressible, you only want vapour going into the compressor.

I wasn't aware there was XJS's of that vintage without fuel coolers, they are mounted a bit further forward on the intake manifold and are a heat exchanger. Similar function, they cool the fuel after it has circulated through the engine and reduces it's tendency to boil and it reduced and chance of vapour lock. Also added heat to the returning refrigerant to boil any liquid. US/Canadian cars were not emissions certified without functional AC as a way of reducing their vapour emissions.

Is your car a Japan market car originally, or built for another market?

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!