I own a 1986 & 1987 XJ6, both series three US market cars. For reasons I cannot comprehend, the low pressure port to add refrigerant is located on a pipe just behind the compressor on the 1986 car, bit it’s located on a pipe near the firewall on the 1987 car, which looks like the spot where the high pressure port is located on the 1986 car. For curiosity I looked for where the high pressure port might be located on that 1987 car, but cannot find it. Does anyone know when and why this location change was made? Even on factory installed R12 systems on these cars, I do hope and believe the charging points for low and high pressure sides were of a different size to avoid potential catastrophe. Any advice and clarification by any listers knowledgeable on this mystery would be welcome. Thanks
Mel R
Don’t recall the exact date but it was only near the end of R12–before the switch to 134a—that the high side port was switched to 3/16 SAE flare to make it differ from the 1/4 low side.
I’m not inquiring about the size of the flare, but, rather, the location of the port. Thanks
The low pressure port on the top next to the compressor is a problem when you convert to R-134a and have to screw an adapter onto it. The adapter sticks up high enough to ding the hood when closed. I solved that issue by removing the adapter after charging, but you’re not supposed to do that.
So, is there any possibility that Jaguar saw the need for such adapters coming and decided to do us all a favor and moved that port to a better location? I seriously doubt that, but I suppose anything’s possible.
So am I correct that the low pressure port on the 1986 car would, in fact be the fitting next to the compressor, and the high pressure port would be the fitting on top of (what I think may be a slightly narrower pipe) on the driver (left hand drive) side firewall region ? If my memory is correct, I do believe I watched a technician add R12 through the fitting near the compressor some years ago. The threads on the ‘caps’ of both the high and low side ports appear to be the same. Unlike newer cars, the folks in Coventry did not mark them ‘low’ and ‘high’, or maybe they did, but when the compressor was replaced by the PO, the port caps were changed . At any rate, if anyone who owns a series 3 XJ6 built in the mid 80’s, but definitely before September 1986, could confirm this, that would be a relief. Thanks
Mel R.
Just to throw more confusion in, here’s the setup in my 1985. I’m starting to think it’s been converted to R134, and it actually works kind of OK (a little weak on very hot days).
Yep, that’s an R-134a conversion. If it’s a little weak on hot days, that’s sometimes an indication it was undercharged – but it can also be an indication that your radiator fans are weak.
These cars were not designed to run on R134 which is less efficient than R12. The system would need at least a larger evaporator and maybe a stronger fan in front of the condenser to make up for the shortfall in cooling efficiency. Regardless the series 3 system does not perform as well as newer cars in slow heavy traffic. In fact, on the air conditioning chapter of the Jaguar factory service manual, when testing operation of the air conditioning system, instructions are given to place a large fan in front of the car to replicate 30 mile per hour driving conditions.
True, but the system was so overdesigned to begin with that the loss in efficiency is no big deal. I converted my '83 to R-134a and got supply air below 40F within 30 seconds of startup.
Nice. Next time I have it to my Jaguar mechanic I’ll have him check the level. It must be holding pretty well as it works about the same as when I got it 3 years ago, although the compressor doesn’t sound entirely healthy- it’s quite clattery at idle.
And your car before startup was situated in a covered parking space. Try parking the car in an outdoor space under a blazing hot sun for more than a few minutes, then start it up. You will not get 40 degrees temperatures coming out of the vents within 30 seconds. You would have to drive the car at highway speeds for at least a few minutes if you hope to replicate that 40 degrees results
You should have your mechanic add refrigerant oil to quiet down the noisy compressor and hopefully extend its life
None of that is true. I got 40 degree supply air within 30 seconds when the car sat in the hot sun in a Walmart parking lot.
Right, I was thinking that too. My Jag mechanic will hopefully know how much oil and refrigerant to use on a converted car.
Absolute old wives tale horseshit. R134a is a thermally more efficient refrigerant. However, because it extracts more heat from the air than R12, it requires a larger condensor to properly disspate the heat which was designed in to cars that were filled with 134a from the factory. However, in conversions this is offset by the REQUIREMENT to fill to only 80% capacity which results in almost all condensors being adequate for the job, with the exception of the automotive world’s equivalent of “hot day denver”, say stop-and-go traffic in Pheonix. In the real world, if done right, with the correct lesser fill amount, a 134a conversion will blow just as cold, and run at lower pressures.
And yes, OP, your car was converted. The high side and low side fittings are different sizes, you literally cannot screw it up.
or stop and go traffic anywhere on a day warmer than 85 degrees F
If that’s the case start looking for the cause, make sure the electric fan is working, make sure the condensor is free of debris and the fins are in decent shape, make sure the system is not over-charged. The single most common thing I see with a converted system not cooling well, other than component failure, is overcharging.
The PO converted the system in my car over 10 years ago and did it right. I see low side pressure around 35 and high side never goes above 180. A lot of shops still look for higher pressure and think ‘moar is betterer’.
If there’s any question about the fill, do a suck-and-stuff. Pull the system down to vacuum, let it sit there for about half an hour, then fill with 80% of the r12 charge. If the reciever/drier is original, change it! It should have been changed during the conversion.
If it was my car, and I was chasing an under-performing system, I would verify no leaks, verify compressor operation, check the condition of the condensor, make sure the evaporator is not partially plugged up with debris in the venting system, and once all that has been checked/rectified, recover the refrigerant, change the reciever/drier and the expansion valve, and recharge the system with the correct fill.