www.jec.org.uk

Has anyone had any experience with the STP products for topping up and indeed sealing (by releasing a tin of sealant into system via low pressure port) the aircon system - the STP website and various product reviews from people with similar issues that many of us have experienced with our Jaguar systems seem reasonably positive? It seems to be an economical initial route to take faced with a small leak which would traditionally entail removing the dash and fumbling in the dark or paying out many, many, many £ notes to get it fixed by an expert.....until the next leak appeared, and so on...
Steve

These sealants do work for small leaks but the problem will be ensuring you have the correct amount of gas and oil in your system as you have a leak. If you do not have the correct equipment to degas and re-gas then better to find a competent a/c outfit who can test the extent of the leak and advise if the sealant will work. Also, if they go ahead and still leaking you will have some goodwill to help find the leak and fix it.
Worst case - as in mine, the evaporator behind the dash is leaking and needs the dash pulling out. Hopefully, in your case is a stone chip in the condenser at the front or leaky seal. Also often overlooked are the service valves which can leak but are easily replaced.

Thanks yes I have a similar leak - but when vacuum tested on refill few weeks ago no issues revealed - now 4 weeks later just a wee bit of gas left - the thing I like about the STP system is that they also supply gas and a valve so that you can check you have enough gas in there before proceeding with the sealant - I thought it was worth a try - top up gas, shove some sealant in and see how it goes rather than take the darn dash out - how big can the leak be in these evaporators?
Will have a shot and let you know - may take car to ATS for a refill (£45) first leave it a couple of days and then have a go....we shall see.
Steve

The issue here is often that the standard leak test is to vacuum down the system and then see if the car will sustain that vacuum for a sufficient period. That's fine but your system is actually under pressure in normal use so, for example, a seal that will be pulled in by vacuum to seal will leak when pushed out by pressure. The real test is to pressurise the system with nitrogen and see if it can maintain that pressure.
In my experience, the leak sealant stuff only delays the inevitable. Better to find the actual issue and fix it now.
If you are going to have the system refilled make sure that UV dye is added so you can see where it us leaking.

Fully agree with davidr - plus access to the pipe seals is not too bad on the XJS compared to other makes.

My XJ-S is pretty good - converted to R134a 10 years ago - has only needed to be regassed once since then.

XJ40 on the other hand needs regassing once a year (£65) in the spring. I have also used this kit from Amazon that stopped the system from wheezing over a winter time once - worked fine - I use the air-con to keep the windows condensation/mist-free-free as well as to keep cool when hot - there is a water leak somewhere in the front passenger footwell area that no-one seems to be able to fix. Here is the link to the kit;
http://amzn.eu/d/aZ1Vkwx

Ripping out the dash to get to the condensor on a car worth £1.5K does not appeal and paying someone to do that would be very expensive. Fix is better than fudge but not at any price.

Taking the dash out is possible at home assuming you have plenty of patience and handy with the spanners!

Disable the re-circ system (not sure how you do that on a facelift though) and open a window.

Worked really well even during this years heatwave.