86 XJ12 AC O ring replacement

I need to refresh the AC system in my 1986 Daimler Double Six (same as XJ12 with 5.2 V12) and I see O ring kits with 35 O rings in them. Is there any source on line on just where all these O rings go or a video on how to replace them? The last time I recharged the system several years ago with Freeze12, it leaked out in a day or two, so I assume I need the O ring replacement and receiver/dryer replacement before I charge it again.

Some parts houses do not list XJ12 but do list 1986 XJS; anyone know if the O rings and receiver/dryer for the XJS are the same as the XJ12?

Phil,
I returned the climate control systems of three of our Series III saloons (two XJ6s and an XJ12) to proper A/C and heating operation after the A/C systems slowly failed over time. I first replaced all of the o-rings with generic green ones that I purchased at a local auto parts store, then tested the systems with a vacuum pump to verify whether or not the system would hold vacuum, and none of them did. Then I tested individual components until I found that all three had internal compressor leaks, but I also had a couple of leaky hoses. I purchased replacement compressors, receiver driers, and hoses and installed them. Once I was able to get the systems to hold about 30 inch Hg of vacuum for a couple of weeks or so, I had them professionally serviced with R12 refrigerant. There was a lot more to it of course like replacing a failed blower motor, two failed A/C amplifiers, a failed vacuum solenoid, and a failed mode selector microswitch to name a few. But I got all three cars to have fully functional climate control systems again.
I used my Jaguar Parts Catalogues to figure out the parts that I needed to purchase and hand selected the replacement o-rings from the generic kits that I purchased.
I am not aware of any online resources to help other than the Jag-Lovers archives.

Paul

Thanks for the reply, Paul.

How many O rings are in the system? I ordered a GPD brand kit from RockAuto that shows 35 O rings in the photo; it’s the same photo on other supplier sites for that kit, but maybe it is a generic photo?. I checked my Unipart catalog and the CAC1881 receiver/dryer is listed as the alternate part number for the UAC RD1137C receiver/dryer I also ordered (surprisingly inexpensive) from RockAuto. The whole shebang of O rings, receiver/dryer, and valve core/cap kit was less than $30 including shipping. I plan to replace the receiver/dryer and all the O rings I can locate and than do as you did and pull it down to see if it holds vacuum. I have used Freeze12 in my other jaguars which I understand is mostly R134a but with an additive that will circulate the original oil for compressor lubrication. I read that Kirby recommends replacing the compressor; If I end up doing that, I’d go to an all R134a system with the associated PAG (?) oil.

BTW, my system did not produce any heat when I last drove it in the winter (I don’t drive it often) so I assumed the servo unit was stuck on cool, and then the blower went silent and I just now discovered that the #13 fuse (15 amp) was blown. Apparently #13 supplies the coil of a relay that supplies the blower through the 50 amp fuse, because I have the blower back and I now have heat and it will cool down to ambient with the temp dial set to cold so the servo must be working even if I don’t hear the little whine of the servo motor I was used to hearing in my XJ6.

Phil,
I have no idea how many o-rings are in the system because there are o-rings inside the compressor and possibly elsewhere that I didn’t change out. I can tell you that I changed out a total of 10 o-rings when I returned the A/C system to full function in my 1990 V12 Vanden Plas (a Daimler Double Six badged for the North American market) in 2018. There are two o-rings on the firewall for the evaporator and expansion valve, two o-rings on the fuel cooler, two on the rear of the compressor, two on the hose from the muffler to the condensor, and two on the receiver drier.
When working on my 1990 V12 Vanden Plas I use three different Jaguar Parts Catalogues to help me sort out part number, XJ12 Series 3 Daimler Double Six Series 3 RTC9886CE of May 1985, XJ6 & XJ12 1968-1992 JHM1147, and XJ-S 3.6 & 5.3 Litre RTC9900CA January 1987 on. Sometimes all three agree on the part number, and sometimes they don’t. That is when the real fun starts. :grinning: The receiver/drier was listed as CAC1881 in two of them, so that was what I purchased.
Your heater problem could be caused by several things. Does your car have the Delanair MK II or MK III climate control system? The MK III has a manual position for temperature control by pulling out on the Temperature knob, and “MAN-AUTO” label beneath the knob. There are many changes between the MK II and MK III so it would be helpful to know which one you have before giving any advice on your heating issues. In the meantime you could search Jag-Lovers archives for “A/C amplifier” or “Heater Valve” to see what problems others have had with their climate control systems. There have been many recent threads about climate control system problems that I recommend you read as they may help you solve your issues.

Paul

Thanks for the O-ring run down; that is exactly what I needed. It will be interesting to see what actually comes in the kit. I had also bought some generic green O-ring kits at the local auto parts stores some years ago, but for the low price I thought it best to buy the specific kit so I am not without a needed one in the middle of the project. My system in the DD6 is the Delanair Mk II with the single servo motor and shaft with all the cams; I’ve also read that the MK III is much different and somewhere I read that the MK III replaced the MK II in 1987, but I am sure my 1987 XJ6 also has the MK II. Perhaps the change came after 1987 along with the model change to XJ40 (which makes buying parts confusing since Jaguar continued to call the XJ40 an XJ6). Good to know the CAC1881 is the right one. Rockauto also listed one that looked like it mounted vertically, but their category was for an 86 XJS and they do not have a choice of 86 XJ12. The diameter of my original receiver/dryer is 1.782" so the one I ordered listed at 45mm should be the same or very close.

I think my system is working OK now except for not having enough refrigerant and the compressor clutch being intentionally disconnected. when I turn the temp dial from hot to cold or visa versa, the blower speed changes to low and then comes back higher as the unit decides what to do; I assume the servo is rotating from one extreme to the other and changing blower speed as it does. Only time and a refrigerant charge will will tell for sure.

Thanks again for the O ring count and locations. I am looking forward to giving it a go. This is a 65,000 mile car that is as original as it can be as far as I can tell. It was originally delivered in Belgium and imported into California by the first owner and I am the fourth owner. Oh, wait. It does have Mercedes marker light that were added on importation, (the same marker lights that were added to my German 86 Sovereign when it was imported new by its original owner), so not entirely original as first delivered.

Phil,
Do not waste you money on a refrigerant charge until your system can hold 30 inches Hg for a week or two. If it doesn’t, like in my three Jaguars, isolate components until you find the leak then replace the component and then test again until you are certain that it holds vacuum. When I worked on the third of my three Jaguars I added another step based on things that I read. I purchased a nitrogen bottle and fittings and then once I verified that the system held vacuum I pressurized the system with inert nitrogen to about 50 PSI to verify that it held pressure as well. Of course I also disabled the compressor. I was tired of throwing a lot of money money at shops to do my A/C work only to discover that the system was blowing warm air again a week or two afterwards due to “new leaks”. Once I verified that the system held vacuum and pressure then I had the last car serviced with R12.
I have two more of my Jaguars to do, but I think I have broken the code on getting A/C systems working again.

Paul

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Indeed, Phil - that fuse supplies power to all AC operations - except power to the fans. The 50A fuse only provides power to the fans - switched by a relay bank controlled by the servo and the function switch…

frank
xj6 85 Sov Europe (UK/NZ)
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Thanks for the fuse function confirmation, Frank, and I appreciate the advice on not wasting refrigerant, Paul. The DD6 AC had stopped cooling in 2006. I charged the system with Freeze 12 in Feb of 2008 and it cooled well at the time. I charged it with Freeze 12 again two years later and had 38 degree air from it. I “serviced” it again in July 2010 but I’ve misplaced my hand written notes from that time, and when I evacuated it and charged it in Sept of 2018 it leaked down to zero static pressure overnight and I haven’t tried to charge it since. I had left it evacuated for an hour and it had held, but apparently that was not long enough, as you said. I’ll try to do it right this time, but I’ll try Freeze 12 again once it is leak free (fingers crossed).

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The pros usually use half an hour or so, Phil - but they may have better equipment for detecting even small leak-downs? One hour steady would be ample for leak detection, but then again; occasionally a leak may occur after testing and fill…

Certainly, charging a system that won’t hold vacuum is a waste of time and money - except as a stop-gap.

Frank
xj6 85 Sov Europe (UK/NZ)
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Frank,
I used to take my Jaguars to those “pros” for A/C work but after throwing thousands of dollars at them, only to have my A/C systems blowing warm again a week or so later, I decided to do a lot of the work myself. Particularly ensuring that 30 inches Hg vacuum and then pressure (50 PSI nitrogen) can be maintained for two weeks or more before getting a professional R12 recharge. In my opinion an hour or two is insufficient to test for leaks, unless your goal is to get paid additional work due to a “new leak”. :wink: I realize that it is usually not practical for an owner or a shop to test for leaks over an extended period. But I have watched my systems bleed down vacuum over a few days so I know that a longer test is needed before an expensive R12 recharge.

Paul

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A lot depends on the shop’s work load that day…and the general practicality of testing for several hours or longer.

Most A/C guys will want at least and hour or two to feel confident. And, in most cases, that’s enough. But “most” isn’t the same as “all” :slight_smile:

Several years ago I had my system charged and the tech was happy with 4 hours. No sign of freon loss since then.

I’ve fairly recently started doing my own refrigerant work. I’m happy with an hour, personally, while acknowledging that in some cases that might not be enough.

Cheers
DD