Automotive Air Conditioning Information Forum (Archives)

Spikepaga on Fri August 10, 2012 8:45 PM

Year: 1995
Make: Jaguar
Model: XJS
Engine Size: 4.0
Refrigerant Type: R134
Ambient Temp: 100
Country of Origin: United States

Hello all. I am having a really difficult time with my Jaguar XJS:

The car has a new compressor, parallel flow condenser, dryer, expansion valve and possibly evaporator. I say Possibly because i am not sure about the evaporator because I am not sure....the only time the car cools properly is after the exp valve is replaced 3x already. It cools for 3 weeks then stops. It has been checked for leaks at the drains and all over no leaks anywhere. Please help

Cussboy on Fri August 10, 2012 11:16 PM

Are the "bad" expansion valves clogged with particles when they are removed?

Spikepaga on Sat August 11, 2012 3:02 AM

Thanks for your reply . They are not clogged when removed , this is the third valve

AutoCool on Sat August 11, 2012 4:08 AM

Heres the fix for your Jaguar. It's most probably NOT the expansion valve but the compressor itself.

The AC compressor has a control valve on the rear plate. Remove the valve cover, then remove the valve and then the spring. Once removed, replace the valve and THEN the spring, (spring on the OUTSIDE of the control valve instead of the inside) and the spring cover with a new o-ring. O-ring is Jaguar part XR81342 if you can't find a match. Should work fine after that.

Spikepaga on Sun August 12, 2012 1:32 AM

Thanks for your reply. I did not mention this on the interest of simplicity on my first post, but the car has had three compressors in the last three years. Two new aftermarkets and the last one was a genuine brand new Sanden from Japan. Not rebuilt. I had them changed in hopes that things would permanently improve.

Would you still say that it's the compressor?

What's particularly strange is that today it was 96 and she cooled like a new car. Whatever it is, it's flaky and intermittent. The air distribution system is a Delanaire 3 and it has been checked for proper vacuum and flap operation more than once. Just to make absolutely sure no air is being mixed in, he heater matrix was completely disabled (no coolant ever goes there now)

Thanks

AutoCool on Sun August 12, 2012 3:17 AM

Sorry that was a service bulletin for a C00344 later model. Does your car have the dual heater fans? Are both working? Defrost should override and run both fans. Have you checked simple things like the cabin filter?

Edited: Sun August 12, 2012 at 3:24 AM by AutoCool

Spikepaga on Mon August 13, 2012 2:42 AM

Thanks for the reply. Everything is working as it should. The car cools intermittently,
Sometimes perfect in 100 degree data, sometimes mediocre under the same conditions.

Spikepaga on Thu August 16, 2012 11:35 AM

The car went back to the shop today to make absolutely sure there are no small leaks. He has told me three times already that the pressures all indicate the system is full, but the last resort would be a leaking evaporator. This is a older Jaguar that requires for the entire dash to come out ($$$). So far he has been unable to find a leak with his sniffer or any dye leaking out of the drains. Does anyone one what is a way to determine an evaporator leak with certainty? I would hate to spend money to have it replaced, only to find the one in there is fine.

Thanks!!

AutoCool on Thu August 16, 2012 5:32 PM

Not really sure how difficult it is for evap access on your car. Might be worth to use a hole saw to open an access to the evap housing and take a peek/sniff around. Sporadic AC problems are tough.

fonebone on Sun August 19, 2012 7:26 PM

Hi Spikepaga; Most here recommend a Ultraviolet dye put into the system, then after you run it a while, you can check the drain tube located under the cowl area for leakage as the water dripping out and down from the evaporator through this tube will contain visible signs of dye, indicating a leak using a UV light. Hope this helps

Spikepaga on Wed August 22, 2012 2:19 PM

Thanks for your replies. Still no hoy with finding a leak, tried untraviolet dye. Might go ahead and do the evaporator,
Question in regards to the evaporator:

It's a very large job to remove the evaporator on a Jaguar XJS...should I purchase a copper evaporator or an aluminum.
Both are Appearantly available.

Thanks

Leggie on Thu August 23, 2012 5:06 AM

Why are you replacing the TXV repeatedly?

What is the compressor doing when its working/not working and what are the respective low & high pressures. You didn't attest for sure that compressor is running and with road noise, you can't necessarily tell if the compressor is running.

Before you go any further, you need to verify that compressor is indeed running when the A/C is turned on yet produces no cooling.
If high side pressure rises abnormally, you must make sure that fans are properly coming on. The fans maybe controlled by a separate relay linked to the control unit so electrical issues can cause fans to not come on as they should.

Multiple relays in series must activate simultaneously after you initiate request for cooling. Any problem in this chain can cause intermittent issues. My car had an intermittent issues due to decaying electrical connections and it was difficult to diagnose, because it was highly temperature and vibration dependent.

Receiver drier should be replaced each time the system is opened. When you said you replaced expansion valve three times, did you replace the receiver drier with it each time?
Did the system hold the vacuum for 15 minutes or so with no creep up after you buttoned up the system and evacuated?

If you only recover refrigerant until system is at 0 psi and you swapped the expansion valve quickly, you might get away with it, but usually opening up the system introduces water that justifies a new drier element.

When it stops working after 3 weeks, how much refrigerant is recovered from system? This will tell you a general idea of leak size or the presence of leak.

Dougflas on Thu August 23, 2012 7:30 AM

To check the evaporator, take a plug and place it in the drain tube. Do not run the AC for a day or so. Then remove the plug and stick the sniffer there. If there is a small evap leak, it should show up.

AutoCool on Thu August 23, 2012 11:19 AM

Quote
Originally posted by: Leggie
Why are you replacing the TXV repeatedly?

Dye in the system, charge holds for just 3 weeks, replaced expansion valve THREE times, and it sounds like it's actually some mechanic doing all this work and not the OP.

Are you 100% sure your mechanic is actually replacing the TXV over and over again or possibly just saying he did?

FIND ANOTHER MECHANIC.

Leggie on Thu August 23, 2012 6:38 PM

He said it "cools for three weeks" and said unable to find a leak, but never stated problem was identified as loss of refrigerant, therefore I can't comment further until he answers the followup questions I posted

Spikepaga on Fri August 24, 2012 1:03 AM

Thanks for your replies.

1) the compressor is always running. I have placed my vehicle on drive with the handbrake on to see if it shuts down. It runs continuously at 100 degrees with the doors open. It is not slipping or otherwise being shut down by the low/high pressure switch

2)the condenser, which is new, and parallel flow, has two small SPAL pusher fans fitted on front that are operated by a switch inside the car. They are new and working correctly. For sure

3)every time I have requested the expansion valve changed the dryer has been changed as well.

4)I have been to 3 Jaguar specialists and the current gentleman is the one who also works on my e-type. He has been working on these cars since the 70's. He is no novice.

There has been a new development. Based on the pressures he took 2 days ago, he felt that a very small amount of refrigerant had escaped. He said around 8oz, but unless he evacuated the system, he would not know. He once again spend a full day looking for leaks and was unable to find any anywhere he looked. Again, based on process of elimination, it looks like the evaporator is the last place left.

Assuming I have a tiny evaporator leak, what is the most durable material for evaporators?: aluminum or copper?

Thanks for your help

Leggie on Sat August 25, 2012 12:51 PM

Quote
Originally posted by: Spikepaga
Thanks for your replies.

3)every time I have requested the expansion valve changed the dryer has been changed as well.

But why?

Quote
There has been a new development. Based on the pressures he took 2 days ago, he felt that a very small amount of refrigerant had escaped. He said around 8oz
You can not know at all. If the steady state pressure is below what PT shows it is, the system is nearly empty. If charge is sufficiently low it will cause pressure readings to read low but you can't quantify how much. He pulled "8oz" out of his rear.

Quote
but unless he evacuated the system
So why didn't he already? In the process of replacing the expansion valve three times, did he not document the amount of refrigerant recovered and compare against what was charged? Not only is recovery of refrigerant required by law, the amount of refrigerant recovered is an important piece of information for examining the presence and magnitude of leaks.

Quote
he would not know. He once again spend a full day looking for leaks and was unable to find any anywhere he looked. Again, based on process of elimination, it looks like the evaporator is the last place left.
I asked what happens when the system is vacuumed and allowed to stand a while after the pump is off.
What happens when the system is then pressurized with nitrogen to 150 psi and allowed to stand?
Nitrogen does not condense like refrigerant nor does it dissolve significantly into oil or hoses, so the pressure remaining is directly proportional to leakage.
Quote
Assuming I have a tiny evaporator leak, what is the most durable material for evaporators?: aluminum or copper?



Thanks for your help

I would go with aluminum if the lines are aluminum. Dissimilar metal connections is an invitation for corrosion.