If this system has been converted to R-134a and is running high pressures due to inadequate airflow through the condenser, one had better hope the conversion included a pressure switch to shut off the compressor. Otherwise it’s going to blow refrigerant out a relief valve – unless it doesn’t have a relief valve, in which case it’ll blow a hose.
I just spoke with the a/c technician. He told me there are no problems with the high pressure side of the system, and confirmed the fans are definitely running properly. the problem taking place now is coming from the low pressure side of the system, which, in his opinion, is an inefficiency in the compressor itself since all other components are in order. He is NOT trying to sell me another compressor. In fact, he suggested the reduced efficiency of my compressor may not get any worse over time and it may operate as is indefinitely. He said his shop has on occasion installed Four Seasons brand compressors in some customers’ cars over the last few years with no negative experiences, so it’s hard to say if there was a quality control issue on the manufacture of my unit, or if the efficiency of the unit deteriorates over time due to its exposure of the heat generated by the XJ6 engine. At any rate, I’ll keep driving the car with a/c as is and monitor the situation. Thanks
Mel R.
Way back when the after market AC in my company car, 57 Chevrolet, was not cooling like my office mate’s car. also a 57 Chevrolet, but with factory air. NO clutched fan on wither car!!
I visited an independent AC shop. The tech used a box fan in front of the car for more air.
He tuned it a bit and declared it as good as it can be. Keep the revs up, one ay or another was his advice.
I considered adding a supplemental fan. Naah, almost trade in time Got a 59 Ford. V8,. clutched fan, factory air. Much better… Coool in any circumstance. Dealer messed up the order and I go the Galaxie. Tbird top. A sweet ride… One of my all time favorite cars… I was sad when trade in time came for it. .
‘Keep the revs up’ seems to be the key. When stopped at a red traffic light for more than a few seconds, putting transmission in ‘N’ and increasing the RPM’s to 1100 seems to make a difference.
On a Jaguar, that might mean you need the belt-driven fan moving faster to get enough air through the condenser. On most other cars, it’s an indication that the compressor capacity is marginal. Back in the day pretty much everyone used drastically oversized compressors (the A-6 is supposedly good for about five tons, enough to cool a house), but more recently cars come fitted with compressors that just barely cut the mustard. Revving them helps.
Last time I was in Las Vegas I was in a rented Dodge. Cruising the highway out of town, it cooled fine. Stop and go traffic on the Strip and the occupants suffered.
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So when the folks at Rock Auto raved about the Four Seasons compressor weighing half the weight of the old heavier A6 compressor, they neglected to mention that the reduced weight also reduced cooling capacity. It would appear now the riddle has been solved.
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I can. That means inadequate airflow through the condenser because the fan isn’t moving enough air.
‘Just what I was going to say, insufficient air at idle being pulled thru the condensor.’
In my experience if you have to replace the fan (the originals don’t last forever and should be checked for cracks passing into the hub of the fan) you must ensure that it is exactly the same diameter as the factory one. If the aftermarket replacement is only slightly smaller this can effect the A/C efficiency at idle. I had to replace the old ‘new’ fan with correct diameter and now all i s ‘A’ OK
Peter
Yesterday I noted some noises that I thought were from the passenger a/c fan, and today the noises were worse, are from the A/C Compressor, and are notably worse when the fan is off. Doing some initial visual observation in the engine compartment, it appears that the A/C compressor has blown oil around some areas that I just cleaned recently. Attached is a pic of the A/C compressor clutch and some of the oily residue deposited within past 2 days from the area between the clutch and the compressor drive shaft. My plan is to try to evaluate the A/C clutch operation and put an A/C system hi/lo pressure manifold gauge set on to see if there is any freon in the system (which I doubt). Anything else I can do easily to troubleshoot? Do you think this is a DIY or shop repair action? I can use AutoZone loaner tools for the pressure manifold and a vacuum pump. Receipts from prev owner show 1 lb or R134 added 2 years ago. Thinking back, A/C cooling rapidly decreased yesterday as I was arriving home, and I probably lost the freon and the compressor oil, then today destroyed the compressor during a short drive.
That clutch is shot. I dunno about this particular model, but those can usually be replaced without disturbing the freon circuit. Might require some special tools, though.
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I agree with Kirbert, Phillip - a noisy compressor clutch is on its way out, and may fail completely at any time…
Frank
xj6 85 Sov Europe (UK/NZ)
Yes and yes, assuming it’s the old A6 compressor…which it will be unless someone installed something different.
Problem is, I don’t think there’s enough room in front of the compressor to use the tools…if you had 'em.
https://www.bernardembden.com/xjs/comclutch/index.htm
Cheers
DD
WOW! Great help and a wonderful repair guide too. I have the smog pump to wrestle with also, and too bad this didn’t fail before I pulled the alternator out the bottom twice in the past 8 months, including last week. That’s how I knew that the compressor problem and dirt was new.
The custom hood lift looks very much like a rig I built to raise and lower my pickup truck bed topper into my garage – back when I owned a pickup. . . .
Say, as a temporary measure, can I greatly relax the compressor belt tension (how?) or must I cut the belt off?
I ‘borrowed’ a R134 pressure manifold tester from AutoZone and I think that I will verify that the freon remains in the system first, if they changed the fittings to R134.
Many thanks to you and everyone else always!
As long as you shop at Auto Zone, you may wish to inquire if they still sell a replacement smog pump. I bought one from them in 2017, turns out the part is also applicable to several GM models as well.
Nonono, this one may not fail completely at any time, is has already failed! You can clearly see that in the photo. The clutch face isn’t even centered in the assembly. It’s fupped.
Hopeful for your insights about my 1987 XJ6 AC system problems. Thanks in advance!!!
You are correct. Looks like the clutch has failed and maybe the compressor. Using a loaner AC pressure manifold have 90 psi on the cold /low pressure side and 110psi high side at idle and a little less than 90 and only a little more than 110 at 1800 rpms. On the good side, there is still freon 134 in the system, but is there a way that I can determine if the compressor is operable and the clutch is not engaged or the clutch is engaged and the compressor is not compressing? Clue may be that the compressor or clutch makes a lot more noise with the AC off than when on, and the clutch end spewed lots of graphite/oil residue around the front of the engine and radiator hoses.
Your thoughts are very appreciated!!
You can grab that forwardmost part of that clutch and turn it (in the direction the engine turns) by hand. It should feel like a compressor, making little compression strokes but otherwise moving smoothly – if that busted clutch doesn’t interfere with it, that is. If it turns smoothly and feels right, I’d just replace that clutch and be done with it. If turning the compressor doesn’t feel right, new compressor time.
Seeing as how you have freon pressure, I’m betting the compressor is OK.
What difference does 1800 rpms make when the clutch is broken?
Thanks for your comments and suggestions! I understand your question about the rpm increase resulting in a slight increase in compressor output pressure, etc., and don’t understand myself. I would like to have observed the compressor pump down the LP side a lot lower and I never saw that. I’ll try your hand turning suggestion – maybe it will tell something. I have been looking at pulling the radiator in order to access the front of the AC compressor.
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The clutch likely still engages, Phillip - but being noisy; it is on it’s way out…
I don’t ‘think’ the clutch is slipping; it either holds or fails to engage - slipping it would immediately fail completely? Mine did…
Frank
xj6 85 Sov Europe (UK/NZ)
No, that clutch is broken. The friction plate is no longer connected to the input flange. If it’s turning the compressor at all, it’s via the occasional jagged edge engaging another jagged edge.