I have been out of the car game for many yrs, this may have been asked time and time again about the A/C on a 84 xjs, mine just seems to blow somewhat cool air, but not cool enough to keep you cool (or sweating on a hot day). I believe I read that the A/c in the V12 XJS are not the best, is that correct. I looked at my compressor, and it is a newer re manufactured one, anf the fill ports seem to be of the nee types. Was thinking of having a shop drain it, run a vacuum and test the system, then fill. Would this be worth it, or should I just try a off the shelf stuff.

Thanks to all that answer

 

AC should be cold. Most likely low on gas. Have it pressure tested this will tell you if it is low. Then go from there.

 

The fill ports are the R134a type? I would put in a can and see what results I got. You have very little to lose by trying it. I would not put in any sealant, or anything that claimed to be anything more than R134a, if it does have to go to a shop they may consider that contaminated and require special procedures, and a lot of your money, to get rid of it.

 

Go to the parts store and buy a simple single gauge fill kit for about $20 that will tell you how low or full the system is..do not simply "add a can" your system only holds so much and could only be down only a few ounces. Mine was recently down about 8 ounces and that was enough to blow "slightly cool" adding too much can be detrimental to the system and could cost you more in the long run.

 

+1 on not just adding a can.

Lots of ways to skin this cat depending on what you feel comfortable doing.

Personally I would spend a wee bit more for a set of A/C manifold gauges ($40-$50 at HF), then you can easily check the high and low side pressures, add refrigerant if needed or UV dye to check for leaks and more.

Cheers,

Allan

 

I'll throw out the possibility the the not-quite-cold-enough output might also be a problem with the control system.

If the internal flaps are not operating correctly, or the system does not recognize that max cooling is being called for, then you might have some air being blended thru the heater core.....which naturally takes the chill off.

One clue would be the vacuum hose to the heater valve. With the system set to max cooling remove the vac hose at the heater valve and put your thumb over the end. You should feel vacuum (vacuum closes the valve). If you don't feel vacuum further investigation is needed. It suggests the system thinks blended air, not fully refrigerated air, is called for.

Cheers
DD

 

Thanks for all the suggestions and replies, last time I did actual work on a vehicle was back in 1974 before I went into the service. And to think, I went to a Trade and Tech HS for Auto Mechanics and worked on a couple of British cars while in school. The teachers had that much faith in the students and courses. I even remember a few I did some work on, but not the exact yr of the car. 57 MG Right Hand Drive, Rewire. Jag XJ6(I believe) rear and front brakes, Rolls Royce Silver Cloud, tune up(one teacher collected and restored cars, he had both his RRs in) Maserati Tune up. Along with a few of the American cars, and a couple of Muscle cars.

 

My only problem is if I go to HF, I would leave with a LOT more than just the manifold gauges LOL

 

LOL, you can always buy online and save yourself from further pain

Seriously though, I think what Doug and I are saying is that it could be a number of things. One thing I have learned well over the 19 years I have owned my XJS is that, if possible, it is always best to find the cause rather than guess at treating the symptom. (Sometimes though that may be your only alternative )
Cheers,

Allan

 

Right.

There are a variety of single faults that can cause this problem.

And, of course, there could also be a stack-up of several faults causing the problem. Individually none may be very significant but in concert they might result in a symptom that is quite apparent.



Yup!

Some faults are glaring, others subtle. Sometimes testing/inspecting doesn't bring us to a concrete conclusion and you have to take a stab at something.

Personally, if faced with uncertainty, I first tackle all the possibilites that don't cost anything to check and repair..... and move on from there :-)

Cheers
DD