[See update below]

Where to start?

With some great coaching from the forum on how to fix my AC, I had determined that the A6 compressor was leaking. I was going to do the Sanden conversion, but I couldn't find anyone who made or sold mounting brackets or adapters for the Sanden. I was going to have to fabricate my own, but never could find the time to tackle it.

Recently, a Four Seasons A6 aluminum drop in replacement type came up on eBay, and I put in a rather low bid and was surprised to win it. Finally, I was going to get my AC running! (If anyone wants a brand new Sanden cheap, let me know).

I downloaded the Jaguar Air Cond HFC Refrig Retrofit instructions, drained the PAG from the new compressor and flushed with Ester oil, then filled it with Ester oil, and installed the compressor, then I replaced the receiver/drier.

Attached my manifold gauges and pulled vacuum. Held 30lbs for an hour. Hooray! The first real progress in tackling this since I first tried 3 years ago. I was really pleased, and looking forward to charging the system.

Jaguar instructions say to put in 1150 grams of r134a. I started with the first 340 gram can, and all seems to be going well, I was unsure of how much needs to be in the system for the compressor clutch to engage, so I attached a second can but it didn't look like the system was taking much more in and I kept waiting for the 'clunk' and it never comes. I closed the valve on the can tap and the low side.

Set about looking at the electrical side of things, checked the fuse, relay, etc. I jumped 12v directly to the compressor, and happy days it goes 'clunk' so I think 'fine, just a wire issue somewhere'. Perhaps stupidly, while the compressor was jumped and working, I thought I'd go ahead and finish the charging of the second can so I wouldn't have a partially full can when I took off the manifold gauges.

Everything seemed to be going swimmingly, and once the second can was emptied, I was going to start looking at the wiring, when suddenly there was 'pop' and a gas hissing starts somewhere behind the engine and a profane expression escapes as quickly as the system pressure. If I had to guess (and it's a guess because I'm no expert) was I blew the expansion the valve somehow or did something stupid.

I'm ready to give up because I can't even begin to see how on earth you get to anything behind the engine, let alone tools or hands. It feels like this has gone beyond my pay grade...

 

Don’t give up!

You are just discouraged right right now because you put expectation to have this solved was not met.

Its a basic AC system. Get your quality parts together and take it to a specialist

 

UPDATE: I guess I suck at giving up as much as I do as mechanic.

I decided to go back out and try and see if I could pinpoint the exact location of the new leak, and I wasn't having any luck putting a vacuum on the system as it would not hold long enough for me to hear any air hissing. So I tried some positive air pressure and was able to hear a hiss, but my stethoscope couldn't find it anywhere around where I thought I'd seen a puff of gas after the 'pop'.

I was genuinely puzzled and couldn't locate the leak. Until I took the stethoscope out of my ears, and thought I heard something faint out of my right ear before the pressure dropped to zero. I re-pressurized, and found there was a new leak in the high pressure hose! It was right at the bend in place that I guess it shot gas out in a line to go just under the throttle body and it must have reflected off the firewall upward and made it look like gas was leaking at the firewall.

I feel a bit stupid, but it's something. Now I have figure out the compressor wiring issue.

 

This might be part of the problem. This is the green brown wire, and insulation is incredibly brittle.

Not certain about how to go about this repair just yet as I would think I would have to go back to the area under the black protective casing, which I'm not sure how to remove.

 

As a temporary repair until you replace the entire harness why don't you put heat shrink tube over it. This will ensure that it doesn't short on anything.

 

UPDATE: I've determined that the clutch is getting 12v, but not ground. If I'm reading the schematic correctly (now there is a big 'if'), the clutch gets ground via HSLP switch.

Does anyone know the minimum pressure on the High Side that will cause the switch to close and connect to ground?

I used the HSLP from the old compressor, and looking at possible replacement switches all I can find are two wire types, but the one from the A6 compressor is a single wire. Does it just ground to the compressor housing?

 

There are 2 types, the earlier cars had a superheat switch, the later ones have the pressure switch. Who knows what the replacement has! It does ground through the switch, an issue I have had is the O ring can sometimes perfectly hold the switch and electrically isolate it from the compressor body, giving an open circuit. Test the resistance from the switch body to ground and see if you have continuity.

I think the switch should close by 50 PSI.

 

Mac
here is my suggestion: If that is the trigger wire carrying 12v, then it runs along the bottom of the V from the bulkhead end. Go and look there and you should find it, make a good joint and then put in a new piece of high temp resistant wire along the fuel rail to the compressor.

 

Something occurred to me regarding the HSLP switch. It's purpose is to protect the compressor; however, if the HSLP switch itself fails "opened" or doesn't ground to the compressor, it will kill the compressor because if it doesn't run regularly the shaft seal fails. A bit ironic.

 

I think the Green/Brown wire and that connector are to the fuel temp switch where it enters the harness to go back to the clutch relay. I believe that is a convertible only option to turn the compressor on even if AC is off via the Mode Control Switch.

EDIT -- It looks like the schematic is wrong, that is indeed the 12v trigger wire. According to the schematic is should be a green/white wire.

 

Here's what I learned today, the compressor harness is completely perished. Any slight movement, and the wire to the HSLP switch loses continuity. Also the connector to the compressor is falling to bits. So, I'll have to fabricate a new one.

It looks like the HSLP switch itself is also inoperable. I was tempted to just wire the compressor directly to ground because I don't want to have pull the compressor AGAIN to swap out the switch. However, I'm in this deep so I guess I shouldn't start taking shortcuts now, so I ordered a new switch and I'll work that into the new harness.

Finally, the big question I need help with. Since I have to replace the high pressure hose, I may as well replace the other two. However, the fuel cooler to evaporator hose scares the bleep out of me. How do you even get a wrench on it, how to not damage the evaporator, etc. Any specific instructions or help how to do this would be appreciated.

 

What I did was use a crowfoot wrench to hold the expansion valve stationary, and then a wrench to turn the nut on the hose fitting. There was some slop in the way the crowfoot for on the expansion valve, so I made sure that I held it tight in the direction it needed to be supported to loosen the hose. That isn't too bad, it's the expansion valve to evaporator that is the difficult one.

What you could also do is put in a fitting with a shrader valve when you make the new hose and put a cycling/protenction switch on that, rather than deal with the switch in the back of the compressor.

 

Mac
By the "high pressure" hose do you mean the one from the compressor to the condenser? If so fine. Then the fluid goes from the condenser to the dryer and from there along the A bank lower chassis rail and across the firewall to the valve on the evaporator firewall. No hoses, all solid stainless tubing from the dryer onwards.

From what you wrote, I got the impression the hose that had failed was the one from the bulkhead (firewall) to the cooler and/or from the cooler to the compressor. This is the return hose, ie the low pressure hose. If this is the case then you do not need to remove the evaporator valve, you just have to remove the hose from the return side of the valve. This return side points UPWARDS and the return hose connected to it points downwards. You need an open ended spanner to fit the large captive nut on the hose, sort of on it at an angle because of the position of the hosenut, and another open ended spanner to support the brass body of the evaporator valve it is connected to, against the torque. This is a touch more tricky, but the valve actually has two cast flats on it specifically for this purpose. You need something that can go down pretty vertically and grip the valve body: pair of plumbers grips or something similar can do it, but you have to hold it using wrist strength to resist the torque. If you are lucky, you will only have to move it about 1/3 of a turn to get it finger-undoable. If the hose is being replace then you can cut the rubber to give more ease, too.
In the attached photo, the

open end you are looking down in is the one you have to undo the hose from.
Here is another pic showing the brass casting and its flats that you have to get hold of:

 

Agree with Greg, and you MUST be SUPER CAREFUL, or a slight twist WILL fracture the OLD evaporator pipe, and basically ruin your day.

Removal of the balance pipe, and whatever else is in the way is just common sense to me.

Our XJ12 (1976) needed the throttle pedestal removing, and some reshaping of the spanners to sit "just right" and then heave hoo, and it came undone.

Alternative, take the engine out, NO, I am NOT silly, YET, and that is what I do whenever the engine is out of a V12 or a XK style 6 cyl, replace the TX valve and the hoses, SOOOOOO bloody simple, and the risk of stuffing the evaporator pipe is almost zero, apart from a stupid move. Engine out in 6 hours, dash out for evaporator, 3 days, the maths are in my favour I reckon.

ALSO

Down here, most A/C repair guys have done them, and worse, and have the tools for the task, BUT, A/C DIY repairs here is illegal, so we simply dont mess with it.

Beer O'clock just ticked over, have fun MATE.

 

Hi Folks, I am going to post in here for some help (hope you don't mind Mac) as I am about to give up on the AC as well on our 1992.

1st the system developed a small leak and the compressor was leaking oil everywhere. We found the leak and replaced the compressor and recharged the system and everything worked perfectly and we drove the car around for about 2 hrs or so while the A/C perfectly ran.

Car sat for a week and I took it out on a warm day to find out that now the system is blowing nothing but warm air..... Big disappointment.

I took it into a specialist to double check our work and have them further diagnose the problem.

They found a pretty big leak and telling me that Evaporator needs to be replaced which clearly is a huge job.

My question is, how did the system ran just fine for 2 hrs and now its not even holding any charge. Can it be anything but Evap? I welcome your help & opinions.

Also, I would highly appreciate it if anyone knows / recommends a shop in Seattle area.

Thank you!

 

It ran Ok because the evaporator leak (assuming it really is an evaporator leak) held up for a bit until the expansion and cooling of it made the tiny fault give up completely. As you may know, replacing it is a dashboard out job; this is quite doable but will take about a day and a half to get the aircon unit out. Actually removing it is a two person job. New evaporators are available but not cheap at about 300 USD or so. Then you can vac the thing and check it holds vac for a few days so you know all is well before refitting it.

Mind you, while everything is out you can do a great deal of preventative maintenance. There are loads of connectors that can be properly cleaned, ditto earth points and battery post feeds.
It is also a cinch to replace the evaporator valve, etc etc. I had to do this as part of my rebuild, and it really does improve the systems functions.

 

I would never consider changing this hose ‘just for fun’ unless I had the engine out for some other purpose. Think about it. The risk is that you damage the evaporator outlet and thereby really gets to a point, where no A/C is a good solution. The hose contains cold, low pressure gas when A/C is working, and the stress is thereby low. It will outlast the rest of the car...

i did by by the way convert a buddy’s ‘85 XJ-SC from R12 to R134a yesterday including oil flushing with the TX valve disconnected and compressor out. Always a tricky job, but I have now made me a cut-open 22mm ring spanner with the right bends on the handle to reach the TX outlet nut. Big help !

 

How lucky am I?
The previous owner spent $4,000 getting the aircon working, he said the car went in to a dark room to sort?
Why I have no idea why, but besides the centre vent not working, now fixed thanks to Warren I could not be happier.
The more I read about non working aircon, the more the blessing I feel, from our XJS gods. I got a good car.

And lets say the fact... that V12 pumps out heat and you cook inside without it.... and I am in NZ not 40 plus C temp some of you poor *******s live in.
We are just hitting winter in June and still 20C today, not usually this way, FA rain and i am on tank water, enough rain to keep the tank full, perfect!

If this is global warming, I say bring it on! Making my life better!

 

Thank You, Greg. You are most likely spot on.

Changing the Evap will be way beyond my capabilities and I will need to hire someone to do it. While the dash is out, I will make sure whatever needs replacing, gets replaced as we intend to keep this XJS for a long time (only has 20K miles on it) .

I am on a hunt for new Evap / Heater Core / Expansion Valve....... any leads would be highly appreciated as I do not want to put used parts unless I really have to.

 

Which one depends on your VIN. Item #8 https://www.sngbarratt.com/uk/#!/Eng...G%20EVAPORATOR