Hi, Gents!

Summer is almost here and its time to get the X-308 air con working again.

Took her to a shop which opened late on Saturday night, but the inexperienced mechanic said the high-pressure charge valve which sits on top of the Receiver Drier Bottle under a black plastic cap is not the proper port to feed in the refrigerant; instead he asked me to show him where the low-pressure charge valve is located.

Is there such a low-pressure charge valve on an X-308?

A picture would be worth a thousand words. TIA.

 

From the x308 Workshop Manual (see attached screenshot)

 

At least one of the side firewall covers and the center rear firewall cover needs to be removed to reveal the low side AC port (steps 2, 3 and 4 in the screenshot nilanium attached). Once these are off, there's plenty of room to attach a charging hose.

 

Yep, the rear cover pops off and it's right there. I had to use that for some AC Pro recharging the first summer I had it when I drove to Louisiana and realized I had almost no cold air.

 

I interrogated the fault codes stored in the A/C Control Module and obtained error code 23 which reads Refrigerant Pressure Switch malfunction.

When the wiring connector was pulled from the A/C pressure sensor, a shallow green pool of fluorescent fluid was visibly accumulated in the socket, indicating the switch has sprung a leak.

After replacing the Pressure Sensing Switch and an R134a refill and condenser hose down, arctic conditions returned to my Daimler X-308 LWB.

 

On the 4th day after the A/C refrigerant recharge, the A/C stopped blowing cool air, and the refrigerant pipe at the Low-pressure filling port did not feel cold at all, with a low-pressure reading of only 20psi. As I needed to use the car, I simply refilled her to 40psi with R134a without checking for codes from the A/CCM as well as trying to add fluorescent leakage detection fluid to the A/C system to pinpoint the exact location(s) of the leakage. Will keep you guys posted after carrying out above procedures. Stay tuned...

 

For future search inquiries.


If your fouled switch is #LJA7658AB I source mine off E-Bay for under $20.

 

Thank you, King Charles, for the video and pricing info.

LJA7658AB is indeed the Pressure sensor which I replaced. I don't know when did you source yours, but I just checked out eBay to find even used ones are being offered for not less than $30.

 

https://www.ebay.com/itm/Jaguar-XJ8-...3/282946672663

eBay item number : 282946672663
$19.99

 

You do have a very sharp eye to locate the best offer on eBay.

Can you also confirm that when the Pressure Sensing Switch has been replaced, there is no need to vacuum/recharge the A/C system because the switch is screwed into a Schrader-type valve which prevents refrigerant from escaping when the switch is taken out?

 

I didn't need to recharge or pull a vacuum. Just don't overfill with AC PRO or you will be buying another switch. You can guess how I know! Might even be useful to leak off some freon to protect the new switch (don't do it if there are witnesses).

 

I rechecked if any codes have re-appeared in the ACCM, but it read 0 meaning none was present.

I used an ultra-violet flashlight going round the entire A/C system circuit and was quite shocked to find the fluorescent dye appearing in far far too many places than I'd expected, especially in many areas of the condenser ... Subsequently, I borrowed an electronic refrigerant leakage sniffer to try to pinpoint exactly where the leak(s) is coming from. Stay tuned for my sniffer test results when I absolutely need to find time to do the sniffing, maybe later today, because the in-laws are coming to town day after tomorrow, and I want to ferry them around in the Daimler to impress them with my English classic.

Incidentally, does anyone have any recommendations for any kind of A/C system stop-leak additives, and how effective or ineffective are they? Has any member actually used it to cure/stop the leak(s) on his A/C system? TIA.

 

Most of the do it yourself freon (AC Pro) fills have leak stop in their formula.