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.

and

 

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.



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?