Just bought a 1994 XJ6.105k miles.4.0L. I need help with getting A/C going. The guy I bought the vehicle from said it is the compressor. I haven't checked myself, but he says the pressure is good. I don't hear the compressor or the fan come on. All lights work on the dash, when I turn on the unit, it seems like super-heated air comes out of the vents. and when left off,front and rear wind screen fog up with sunroof and windows open. I'm in the south, that's the only way you can stand to ride in it this time of year.

If anyone could let me know where to start , I would appreciate it.

 

Welcome , have your R134 checked I think there should be huge loss on it or check blue relay into the engine bay .
I also had some problems with my A/C in the past which I find pretty irritating

 

Thank you for the response. I will check 134 level. I have the gauges somewhere, just have to go dig them up. Also I have a couple of other junk vehicles (not Jags) in the field that have the same relays in them. I'll do some swapping out and see what I come up with. I'll post results back in a bit

 

Sorry, for the delay. The Jag quit on me and the wife 40 miles out of town on 9/11. Ends up it was a good thing. The shop I had to take it to specializes in Jags, BMW's and such. Yesterday i tried charging the A/C. Got about half a can ( about half of an 18 oz. can), the compressor clutch squealed and put out some blue smoke. I turned it off and on a couple times,seemed to quiet down some, but the air never did cool. The pressure showed between 20-25 psi. Left it for 3-4 hrs. tried to put more 134A in,checked pressure before i started , it was at 100 psi. What's would cause that? When I turned the A/C on a white mist was coming from the compressor,was that the 134A? could I just change out the clutch on the compressor or is the whole thing shot ?

 

No one out there knows what I'm talking about ? Are there no A/C Trouble shooters ? Did I post to the wrong forum ? I really love my Jag . I took a trip down to the coast the past three days. talk about a HOT **** without A/C !
Not asking for sympathy , just wandering if I could catch a break on some repairs or is it going to be another 600 plus $ ?

 

With any A/C compressor, I don't think it's possible just to swap out the clutch...you would need to swap out the whole thing.

 

I have experience with household A/c units, I know the principle though.

At 100 degrees F the R-134 needs to be compressed to 125 Psig to condense. Lets work with these numbers for simplicity(you would need to figure out what numbers work best for you). So you would need to give the system a base charge of about 50 pounds. Then you would turn on the a/c unit and charge the system untill you reach the desired PSi for the temperatures the high site will have. Remeber it will go through a condenser to cool the gas down to near ambient so you don't need as high of pressures. If you have means to measure the temperature when it enters and exits the condenser then you can tune the system for best operability.

However this is probably beyond the scope of your means and most peoples means so I would charge it untill the high side reached about 100 psig and see where that got you. Remeber start with a base charge and charge slowly, give the unit about one or two seconds of charge and then wait a little bit to let the system absorb the r134a and stabilize. As soon as the a/c gets cold then you would add a little bit more and drive on it to see how it works.

If air got into the system then the system will require a full vacume and oil change(out of the scope of most home mechanics)

It sounds like your compressor is caput that could be due to lack of r134a and to much air in the system, water in the system, not enough oil/bad or dirty oil or an overcharged system.

If I were you I would take it to a shop and diagnose it since your compressor is most likely dead...

 

thanks for the replies to this thread. I apologize for not responding , I haven't received any e-mails notifying me that there were responses. i should have been checking anyway.
The A/C has been put on the back burner for the mean time as we have had one of the coldest winters here in the south for 25 years.
Also I've had other problems to work out with the old girl. I do have to be careful when disconnecting and reconnecting the battery , because I think the system defaults to have the A/C on upon the first time you start it up after reconnecting the battery . I start her up and can't figure out what that horrible squeal is and the look down and the A/C on button is illuminated . push it off and all is well.
When things warm up I will replace the complete compressor , I have done it before on another vehicle. I have a buddy that lets me use his vacuum pump.
Thanks again for the replies , I'll save this post for when I do the job.