'94 XJS 6 Cyl AC problems

I had the AC serviced in June 2020 and all was good until Sep 4th. Turned on AC and just got warm air. Next morning i did some troubleshooting. I started the car and AC and looked at the compressor, clutch is not engaging and the pulley is just free turning. I Immediately checked the fuse on the passenger side box and the one for AC 5 amp fuse was blown. Put in new fuse, and started car and AC and it blew again. Also noticed the AC fan that cools the AC radiator wasn’t running. Disconnected the plug going into the fan, left the fan plug disconnected and installed new 5 amp fuse , started the AC and blew another fuse. I would guess it is one of thee things.The clutch on the compressor, the compressor itself, or the AC fan. A few questions: if the AC is turned off, does the AC fan also shut off? 9I would guess yes). Also, if the compressor clutch is faulty with the AC turned on does the AC fan shut off? Also if the AC fan is burned up, does that shut down the clutch on the compressor as a fail safe method to protect the whole system? Thanks and any and all help is appreciated.

Sandra,

You say that the fuse blew again with the fan plug disconnected. Normally this would mean that it’s not the fan but either the clutch, the relay or the wiring in between.
Try disconnecting also the clutch to see if the fuse will blow again.
Next step would be to get a multi meter and check the resistance of the coil, or any possible short in the circuit.

Starting from the basics - I would make sure that the gas is sitll in the system. The fact that it was serviced in June means nothing… Or even worst - service coud be done incorrectly.

I haven’t had any leaks so i assume that the system is still charged.

I will disconnect the clutch and put in another fuse and see if it blows. Thanks.

Today, after I installed a new fuse, I disconnected the plug leading to the clutch and started the vehicle. The AC fan came on and while utilizing a circuit tester with a light, I had power at the disconnected plug leading to the clutch. I would assume that means the clutch is shorted out and needs replaced. I didn’t put the plug back together as the fuse would just blow again. I don’t believe there is any other test that i could do to prove some other component such as the compressor is at fault. My question now is: is it possible to remove and replace the clutch without removing or disconnecting the compressor? Looks like the bonnet will probably have to be removed. Not having to remove the compressor means i could possibly change the clutch myself without having to take it to a mechanic. Anything i need to know about how to change the clutch? Special tools, etc? What do you think?

You could use a VOM to check the ohmage of the clutch.

Yes, you can definitely do it your self, but before you start measure the clutch to be 100% sure that this is the problem.
You need to get two extractors, very common and easy to find as the GM A6 compressor is used in many many cars.
All you need to know is in this great article by @Bernard_Embden.
https://bernardembden.com/xjs/comclutch/index.htm

If this is a '94 6-cyl, it is not a GM A6 compressor.

oups, missed the 94 part… me bad…

It’s likely the same as my 1996 Sanden SD7H15 compressor.

Common, and shouldn’t be too difficult to remove and replace. I don’t know if I would bother with diagnosing parts. A rebuilt compressor is easy to find for under $200.

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Yeah, but that involves a discharge and recharge of the freon circuit. Replacing just the clutch should be doable without disturbing the freon circuit. And I’ll bet it’s doable.

Yeah, clutch kits are widely available:

https://www.google.com/search?q=clutch+for+Sanden+SD7H15+compressor&oq=clutch+for+Sanden+SD7H15+compressor&aqs=chrome..69i57j33l4.11747j0j7&sourceid=chrome&ie=UTF-8

Ya gotta pick one with the right pulley, though. Count grooves.

Thanks so much. I plan on my mechanic doing this and i will give him this info.

changing the just the coil saves looking for the full clutch, and can be done “in place” on the Sanden, without opening the circuit : I did this on my 93.5 V12

the coil isn’t really easy to measure, as it’s quite low (about 4 ohms) and has a protection diode in the circuit
the coil on my car was “half shorted”, with a resistance of about 2 ohms
for testing, I used a thermal fuse in the same dimensions as the 5A fuse, so I could verify the clutch activation

more info and pictures on the thread