Finally got around to investigating issues with the A/C on the recently acquired XJ40, driven by the rapidly rising temps here.

Observations:-
The fan responds to the dial on the dash, getting noisier and more air flowing, but it is never quite the hurricane you get in modern cars, is that normal?
There is a lot of ducting visible in the passenger footwell, but it feels connected.
Air does flow from most ducts.
Car would have been R12 from new, but has R134a stickers and connection ports applicable to R134a.
If the car has not been started for a while, 2-3 hours, then the a/c clutch will engage on the compressor when the engine is started. It runs only for a minute or two then, then disengages. no positioning of the controls can get the clutch to engage again.
Connecting a parts store refill can with gauge, suggests low to no pressure, but attempts to add more refrigerant do nothing.

Questions:
What's wrong? Is it underfilled, overfilled, or an expansion valve issue?
What causes the clutch to disengage, low pressure, or high pressure, or?
How much air should be coming out the ducts?

I read about broken flaps and non-rotating valves, so I guess I need to investigate those a little further.

I reckon I will be calling the local shop tomorrow, but the more information I have, hopefully the less ripped off I will be.

Still needs fuel tank leak fixed and new hifi sorted, but at least the brakes, engine and transmission seem fine. One step at a time.

 

I have a couple of thoughts. They may be worthless, but here goes. On my 92, I had an A/C compressor self destruct. Apparently the vanes broke loose inside it. I replaced the compressor but a "bit" of stuff had plugged the line and caused a no-cold condition. I have not corrected it yet. Maybe you have a bit of something plugging a line? As far as the air flow goes, I would try testing both fans. I have not had this happen but they seem to be prone to rust and not working. If only one is working, the airflow will not be satisfactory. Good luck.

 

 

NTL1991, thank you thank you, thank you for the clear explanation and logical step through.

I might have a go with a set of gauges this weekend, I know where I can borrow from, but previously struggled with AC on another car, and finally took it ot a shop that sorted it for $100 (empty, recharge to correct amount).

I have booked them again for next Monday, so they will remain the backup plan.
I'll let you know how it goes.

 

Left the car at the A/C shop last night, just waiting for the call now on what they found.
I washed the car before taking it over, to pretend it is much loved and should be treated nicely, and got very wet feet on the drive over, so I need to look into drainage issues. Hoping that does not mean corrosion problems on the A/C electronics etc.
Also noted that the air temp never changed whether the selector was on hot or cold. Gauges were a bust, missing o-ring meant they did not connect properly, did seem to suggest low pressure in the system though.
Scared myself reading through all the issues there could be on the system, could be a lot of troubleshooting to check everything out.

 

 

A/C shop appears to have performed a free visual inspection and concluded that there is a leak at the compressor and at the expansion valve. Based on that, they are quoting $1500 for those two parts, an air dryer, and usual emptying, testing and filling. He did mention a lack of experience with jaguars, and having been bitten by one before and gave me the name of shop that focuses more on European cars.
Off to get the car back, then I guess I will be clearing ducts, check vacuum systems and probably buying an Autozone dye kit.

 

Get yourself a UV flashlight and look at the compressor and expansion valve fittings in total darkness - you'll be able to see where the leaks originate from as more than likely there is already dye in the system.



Often it's the o-rings that leak at the connections, and they won't run you $1500 ...


Larry

 

I agree with Lawrence. This is definitely not a $1500 job... And any A/C shop that says they're unfamiliar with Jags or European cars don't really have any business doing A/C work... The compressor is a standard General Motors A6 used on almost every GM car built from the late 70s to the late 80s, there are no funky fittings, connections, mountings or anything like that at all.

You can get an entire "rebuild" kit from RockAuto.com for $289 with a NEW (not rebuilt) A6 compressor (with appropriate seals for R134a, which yours most likely does not have unless it was converted to R134a at the dealership), NEW Receiver/Dryer, and NEW expansion valve. For $75 more, you can replace three of the hoses with new barrier hoses compatible with R-134a. A brand new condenser is $80. A/C parts are NOT expensive for this car...

If you can turn a wrench and don't mind getting dirt and grease on your hands and forearms, you can replace all the components yourself, and bring it to a capable A/C shop for a ~$100 evacuation and recharge.

If you just need a bottle of oil, O-ring kit, expansion valve, and receiver dryer (always replaced when the system has had leaks or is opened for work more than minutes), you're at about $50 in parts...

Check with UV light, especially around the bottom of fittings. Check for greasy deposits. Check around the front seal of the compressor too.

-Nick

 

Awesome, this is what is so good about a family of enthusiasts supporting each other.
I have no idea if the conversion was done at the dealer or not. The hoses have R134a fittings, does not look like they are adaptors screwed into R12 fittings, so I was hoping the hoses had been swapped indicating the job had been done well.
The Shop commented that it did not look like the compressor had ever been changed, but I know the TSB said it would only require a seal swap. I think maybe the quote was his way of saying that it might not be worth spending that much on a 30 year old car. As I said, he charged nothing today and a few years back we had a good deal where I did the mechanicing and he did the test and charge. I trust him.
I will get to researching and investigating and keep you all updated (although progress will be slow!).

 

Progress has been made.
The duck bill was indeed flowing slowly, did not seem to be full of debris as much as just fused shut. Squeezed it open from the sides and the flow rate was greatly increased when pouring a can of water down the scuttle. I guess I will know the problem is cured next time I wash the car then go for a drive.
Removing fuses from each footwell fuse box confirmed both fans work and the error messages on the dash display came up, so that checking works too :-)
Topped of the coolant reservoir, it was a little low, ran the engine for about five minutes and the air coming out of the vents felt warmer than ambient.
IR thermometer suggested it was around 110-120F, does that seem appropriate (it was around 80F outside last night)?
Dumbbutt confession, I had been looking at the air pump not the A/C pump. I guess I had not really focused on the A/C system as I tended to everything else on the car, and a quick look had found a belt driven pump with a clutch on it, so I assumed that was the A/C (same position as my old Series III). Actually looking at the A/C system last night, following pipes, looking for oily residues, led me to the real A/C pump, doh!
Confirmed that the pump does actually run quite a lot, but does turn off when told to (fans off or full humidity setting), so that is promising.
I was also able to confirm that if I set the temp to max cold, the temp at the vents did start to drop, even if only 5-10F. Not sure if that is a result of A/C, or just bringing in more ambient air?
I also got out of bed at 10:30, due to my mind racing through all possible next steps, and went outside to shine my new UV flashlight over the system. I saw no signs of a dye. So either no dye in the system, or no leaks. I could not convince myself that the sight bubble was glowing more than background, so maybe no dye in the system.
Off to Walmart tonight for a 10oz can of dye/sealant/R134a. New fittings arrived for my gauges (it seems I am not the only one with a Mastercool set with a missing o-ring!), so I should be able to get pressure readings and then add the dye. Hopefully that will be us one step closer to finding the issue.
Onwards and upwards!

 

I wouldn't use the sealant, that's a one way ticket to goopville, with no return. Get a can of 5 oz dye/lube that dispenses 1oz from oreillys or autozone.- much better idea.

If your compressor is running, you must already have pressure in the system, right?

Larry

 

Thanks Larry, that was the aim of my post, see if there were comments on that.

I am assuming that there is pressure, or the switch would have tripped the compressor, right? So maybe there is still some life in it. Hoping the dye shows an obvious fault, or no fault at all, and getting the pressure right restores the system, even if that is only for a short-ish period, it should all be good information.

A lot of advice says to empty and then refill with a known weight, does anybody think I can get it working using only gauges, or is that advice right? I am prepared to buy scales, pump, and 40lb of R134a if I have to, but the emptying will likely mean a trip back to the A/C shop, as the recovery stuff seems expensive, assuming there is some pressure in the system.

I am thinking dye and a can or two of R134a is something I could do this weekend. If that does not work, then order more equipment and new parts and try again the next weekend.

 

We have extreme summer conditions in Dubai with temperatures reaching above 122 F so a cool A/C is a must.

I have a 1988 Jaguar XJ-SC that runs on R12, i still use that cos it is available here.

I believe that R12 is no longer in use or banned in the USA now. However, R414b works fine be used safely with no conversion needed.

 

 

 

Thanks Nick, that pdf is very informative. I had read that the recharge was only 32 oz though, but I guess Jaguar are the experts here!

Yeah, I am cautiously optimistic that maybe a recharge will help, if not the dye should confirm where the leak is.

The gauges I have are Mastercool, they seem functional enough, now I have changed the couplers for a better brand.

I found online that O'Reilly will loan the pump ($170, refundable on return) or Amazon sell them for less than $70.

I was considering the 40lb tank ($160), as being in CA, the R134a seems expensive, has $10 deposits on each can (90 day limit on return time) and now a friend has mentioned he could do with a recharge too and we have three other cars that might need attention, so it would likely be cheaper in the long run. Proper scales look like they are $70, but as you say with the gauges, they pay for themselves fairly quickly. Or I can check if anyone loans/rents them locally.

I did not get time on the car tonight, assisting a neighbor with pool pump issues, but hope to get time over the weekend

 

O'Reilly will loan the a/c pump?!?!?!? What am I waiting on!

 

Jerry, I know you are smarter than that, so I assume you are just trying to take the Michael, but for clarification, just in case you do plan on embarrassing yourself at O'Reilly, Nick was talking about a vacuum pump, not the A/C pump.
There is also likely a 90 day limit, or is it 30 days, on how long you can borrow it for and still expect a refund. Up to you if you want to drain and refill your system every month
Cheers,
John

 

I added a 12 oz can of R134a with dye in this morning. pressures before and after were:-
engine off, a/c off, 90/90, engine on, a/c off, 90/90, engine on, a/c on 5/90 (5 might be a generous figure, more 0-5), after adding can 35/145.
Temperature in the workshop was around 85-90, hotter nearer the running engine. Temp in the car was around 100F and on the footwell ducting it was around 91F with the A/C going full pelt.
Electric fan on the front of radiator was running, and kept going for a little after switching off, which I believe is correct behaviour.

At $10 for a can of R134a, I am tempted to go buy another 1-2 cans and see if I can get the pressure up to ~50 which is where the tables suggest it should be for this ambient temperature then see if the system can hold that pressure. No immediate signs of the dye leaking out anywhere :-)

The dye is now clearly visible in the sight glass, frothing, but I believe frothing is a symptom of low pressure, and might always be present in a system designed for R12, but now running R134a?