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Marginal A/C performance after 3 compressors no Jaguar XJS  Pages: 12

Spikepaga on Thu August 11, 2011 1:02 PM User is offlineView users profile

Year: 1995
Make: Jaguar
Model: XJS
Engine Size: 4.0
Refrigerant Type: r134

Hello all,

I really hope someone can help me with my A/C

As of the latest "overhaul" last month the car has:
1-Brand new-not rebuild-original sanden compressor obtained thru Sanden in Japan
2-Parallel Flow condenser with two 9' Spal pusher fans in front of it.
3-New dryer
4-New exp valve
5-Evaporator is less than 2 years old
6-Heater valve is new and operating properly
7-Delanaire vacuum system/flaps are all routing air theu evaporator, NOT thru heater matrix.
8-Mechanical fan clutch in car is new
9-No air leaks around condenser
10-I do not have the pressures but two shops indicated that the pressures where perfectly within range-both the shop that did the work (Jaguar specialists) and a second A/C specialty shop

After all this I have noticed that at 100 degrees my A/C wil sometimes freeze and sometimes with just take humidity out of the air. I have always thought that A/C systems are slightly undercharged , so I added 3/4 or less of a r-134 can. Definately less than 10oz to a system that was supposedly fully charged to spec . As soon as I did that the compressor started cycling on and of and air got warmer and I thought I ruined my new compressor. I purged some freon , and soon the compressor was running like before, and performance was like before. Soon I realized that the high pressure switch must have detected pressures over 400 and shut the compressor of.

Now I know that overcharging is not a good thing, but surely adding 6-10oz to a system that has the right amount on it is not enough to A)kill the compressor, or B) throw pressures above 392 to get high low pressure switch to kick in...

My thought is that either the high pressure switchis cutting of the compressor early, or the evaporator temperature switch is incorrectly thinking that the evap temp is zero and shutting of the condenser. That would explain the flaky behaviour.

Sorry for all the information, please share your thoughts on this.

Jase007 on Thu August 11, 2011 1:14 PM User is offline

Buy yourself a proper set of manifold AC gauges for $75+ and read the pressures yourself then ask Qs here. Adding r134 and then venting by hand is shooting in the dark.


1999 GMC K1500 Suburban SLT
5.7L Vortec with C69 Rear Aux Opt,

bohica2xo on Thu August 11, 2011 2:03 PM User is offline

1) Without a gauge set, all you are doing is guessing.

2) A 25% overcharge is enough to cause all sorts of problems.

3) Venting refrigerant on purpose is not legal

You "think" that all systems are undercharged. I guess all the time they spent designing those systems was wasted. Charge levels are arrived at with actual testing of as-manufactured systems. Any changes should be made with accurate gauges installed and a clear understanding of how the system operates. Along with a half dozen thermocouples in the right places...

You "think" the HPCO must be faulty. Not because you have observed it dropping out at a lower pressure with the gauge set attached, but because it appeared to work (no gauges!) when you overcharged the system by about 25%. You are lucky it DID work, or a piece of that compressor might have taken your head off leaving the engine bay.

The fact that your evaporator freezes says the refrigerant loop is capable of good cooling. Most likely a control issue, but you still need to check system pressures. A Mitchell subscription would go a long way on troubleshooting that control system.


"Among the many misdeeds of the British rule in India, history will look upon the act of depriving a whole nation of arms, as the blackest."
~ Mahatma Gandhi, Gandhi, An Autobiography, M. K. Gandhi, page 446.

Spikepaga on Thu August 11, 2011 3:38 PM User is offlineView users profile

Thanks for your reply. Your information is very helpful.

The only reason I mentioned, in my ignorance, that sometimes A/C systems are undercharged is because every single time I have taken my *other* vehicle to the dealer for a "A/C Check", upon leaving the shop that car has performed poorly and I have always had to add a can of freon for it to work as before.

The vehicle in question, however, has had 3 compressors, 4 dryers, 2 exp valves, 2 condensers and 1 new evaporator in the last 3 years. The repairs have been done by reputable mechanics who specialize in older Jaguar vehicles and their A/C systems. The parts have never been replaced due to failure, but rather because I have assumed that the parts where not up to par and have replaced them with OEM new parts.

Before I added the 8-10oz of freon, maybe less, I took it to the shop that installed the last bulk of parts, and they said the pressures where perfectly fine. He mentioned that he had filled the system to 30oz when the parts where replaced. The system specs are 1000g or 35.5 oz.

This is why I added the freon. As I mentioned earlier, after driving the car for 1 hour and realizing that the system actually was blowing warm air and the compressor was cycling on and of, I purged as much as I could until things returned to the previous state.

I wont be able to buy a set of gauges until next week.

My biggest fear now is that if because the system was overcharged for 1 hour with 5-10 oz of extra freon does it mean that there is some type of catastrophic failure bound occur in the near future??

I know its almost impossible to help someone without pressures, but any input is greatly appreciated.

Cussboy on Thu August 11, 2011 8:23 PM User is offline

Originally posted by: Spikepaga
The only reason I mentioned, in my ignorance, that sometimes A/C systems are undercharged is because every single time I have taken my *other* vehicle to the dealer for a "A/C Check", upon leaving the shop that car has performed poorly and I have always had to add a can of freon for it to work as before.

Refrigerant is NOT a consumable. If it is low, then there is a leak. Find and fix the leak. Adding refrigerant to a leaky system is simply a band-aid, and I believe might be illegal (except to help test for a leak).

JJM on Thu August 11, 2011 8:25 PM User is offline

Are all the parts that have been replaced brand new, original Jaguar parts?

How much oil was added to the system?

And yes we do not pressures, particularly readings when the system is not performing properly (tape gauge set to windshield if need be).


When considering your next auto A/C purchase, please consider the site that supports you:

NickD on Fri August 12, 2011 6:18 AM User is offline

Stating "flaky behaviour" rather than "erratic behavior" hints you are not writing this in the USA, so wouldn't be appropriate to dictate to you the laws of this country.

Fortunately or unfortunately, the Jaguar is not on my list of AC vehicles that I have worked on, last time I drove a Jaguar was back in the 50's, not only didn't it have AC, but didn't have a roof either. I would have to know the system. Freezing evaporators can also result from a cycling switch set too low in a CCOT system or an improper operating temperature sensor located in the evaporator in a TXV system that cycles the system if its temperature falls below 33*F. Its far more typical to have a home AC system freeze up due to low refrigerant, they normally don't have sensors for this, practically all automotive systems have such a control, if the pressures or temperatures are too low, automotive should shut down. Yet another cause for freeze up in a home system is insufficient air flow. Yet another sign of a properly charged system is the outlet temperature of the evaporator tube, should be about the same temperature as the inlet.

Proper charging in practically all systems dictates a bubble free liquid line at 85*F with the engine running in the 1,500-2,000 rpm range, AC on, blower at maximum, and the doors opened. Some vehicles are kind enough to have a sight glass for this purpose, use to be standard in the USA first systems, dumped it to put more money in the stockholders pocket. Pressures do tell the same thing. But just like on our latest vehicles, would only add a couple of bucks to display trouble codes, the codes are there with all the circuitry to form them. But as it is, want you to spend over 5,000 bucks for an external scanner just to display the damn things. Damned OBD II connect, cabling, serialization of these codes cost more than a simple display unit.

But even if you do have a sight glass, not enough in a MVAC system, still require gauges, its the only way you know if your control devices are working properly along with other test equipment.

Then you run across a vehicle that has an insufficient capacity AC system. Can ask Bohica about his Ford explorer, better yet, not, you will piss him off again. Had an 86 Honda Civic hatchback like that, not only did I have to drive that damned thing over ten miles before I got any heat out of it in subzero weather, a cool breeze was the best the AC could do on a hot day. Way too much heat load and volume in that vehicle with a toy for an AC system.

So how is your Jaguar? Posted what you had done, but did this thing ever cool worth a damn? Isn't it this car where you have to remove the windshield first before replacing the evaporator?

NickD on Fri August 12, 2011 6:26 AM User is offline

Oh, Freon is a registered tradename of DuPont for R-12 refrigerant, guess them calling R-134a, "Suva", really hasn't caught on yet. Really don't mind you calling Suva, free-on, but when I hear a so-called professional charging an R-410a system, free-on, wonder what kind of idiot he is.

Just a point of interest, in the 110 year history of refrigerants, there are over 4,000 different types of refrigerants. We have but a small number in common use to memorize, but not easy if you were born with a photographic memory that is now way overexposed.

Spikepaga on Mon August 15, 2011 11:57 AM User is offlineView users profile

Thanks Nick for the information. I finally got a real set of gauges, which I probably do not know how to use properly, but these where my results:

At 10am 87 degress heat index 95 the pressures where 65/200....

What does that tell you guys??


TRB on Mon August 15, 2011 12:04 PM User is offlineView users profile

Anyone noticing the trend of high low side pressures lately?

How much oil is in the system?


When considering your next auto A/C purchase, please consider the site that supports you:

Spikepaga on Mon August 15, 2011 1:37 PM User is offlineView users profile

Thanks very much for you message

No ,the amount of oil should be correct.

When my shop replaced the compressor, condenser, drier and exp valve 1 month and 1/2 ago they flushed the system and added the correct amount of oil to it.
-Again, keep in mind that the parts where changed not because anything failed-but rather because I though that replacing the aftermarket compressor with a OEM new Sanden compressor and replacing the OEM serpentine condenser with a parallel flow condenser would surely increse performance (This sytem came with r134 but Jaguar kept on using the serpentine condenser). The system continued to perform just like the one before it and the one before it. These cars suffer from airflow problems, so I thought a parallel flow condenser with two pusher fans in front would do the trick

The only change that I have made since the above mentioned repairs was to add 8 oz of extra r134 in despair, which resulted in the new compressor cutting in and out. I then purged some freon until the compressor was running constantly like before in the 100 degree weather at idle. It has been made clear that this is a poor way of dealing with a cooling problem. Got it.

Knowing all the facts,the parts that are new, the misadventure with extra 10oz of gas, what should I do?...I am very interested in knowing if adding 8 or 10 oz of r 134 and then purging a good amount of it (after about an hour) means that I should go out and buy more new parts??? or does it mean that I need to have the system evacuated and recharged????

Obviously I would like to avoid spending any money unnecessarely and hope that adding and then removing the small amount of r134 does not mean that I have destoyed something or that I need to pay an hour of labor to evacuate and recharge

Spikepaga on Mon August 15, 2011 4:02 PM User is offlineView users profile

Guys, sorry I think those readings I took this morning where no good. Sorry I am new at this a/c gauge stuff. I just realized you got to at least rev the car once, for it to show the real pressures

So I went to lunch to try the gauges again. I tried two tests: These where the conditions:

Temperature 99 degrees (Heat Index 104)
CAR IDLING ON PARK NORMAL-650-700 ie not reving
LOW SIDE:little over 60 but less than 65
HIGH SIDE: steady at 300

Temperature 99 degrees (Heat Index 104)
LOW SIDE: little less than 60 might have been in the 50's
HIGH SIDE: could not see clearly, but it seemed to reduce as well.

I am going to have to try this with a buddy to rev.

How does that look??

Edited: Mon August 15, 2011 at 4:06 PM by Spikepaga

JJM on Tue August 16, 2011 12:01 AM User is offline

You know Tim, you happen to have a good point. What's going on, they all seem to have very high low side readings??? Part of it seems to be a lot of the silly kit usage, but even those who are performing proper repairs seem to be running into the same issues.


When considering your next auto A/C purchase, please consider the site that supports you:

NickD on Tue August 16, 2011 4:49 AM User is offline

Absolute lowest vent temperatures you can get with a 60 psi low side is about 65*F, probably more like 70*F. Not very good. It looks poor to me. Still don't know what kind of system you have. Tim suggested too much oil, I can suggest, too much air in the system and that is extra bad with PAG oil.

Most shop manuals print out a P-T performance curve, what kind of pressures you should have with variations with ambient temperature, RH also plays a strong role along with a trouble chart if your pressures are too high or too low. With high humidities, your evaporator drain should be dripping like crazy.

Since I seem to work alone, use a wedge in the carburetor or the throttle body with an accurate engine tachometer.

Recall reading where Ford took over Jaguar, said their engineers could improve their quality. At that time Ford was having huge quality problems of their own. And in regards to designing a good AC system, ask Bohica about his explorer. On second thought, don't, will piss him off.

Anyone here know what kind of system this thing has? Could have purchased a Jag quite reasonable a few years back, until I looked at the replacement part cost. Are very nice looking automobiles.

Spikepaga on Tue August 16, 2011 4:24 PM User is offlineView users profile

Thanks you guys for being so nice to continue to reply to these posts, I greatly appreciate it .

Well...First I found out that the pressures have to be taken with the car at 1500 rpm...constantly...I though I had to rev it up to 1500 and then let it fall back to 700........(head slapping moment)

Anyway, I proceded to hook up the gauges...when I tried to move the dials so I could see them I accidentally opened the low side port (the only one you can open with these gauges...and for 30seconds to 1 minute refrigerant and I guess oil spewed all over my windshield (this is a old jag so the hood opens backwards) I got the gauges out, retightened and proceeded to test again.

At 1500, ambient 87-90 6.30 pm, the low side was 35 maybe a little less and the high side was 250 ish, I do not recall.

However, the car froze all the way home. I have not had a chance to test it, but it had not been cooling this well even at night or early in the morning.

What the hell do I do next? Add oil back in? Its cooling fine, but How do I know if too much oil escaped??

Thanks a lot

TRB on Tue August 16, 2011 4:29 PM User is offlineView users profile

Originally posted by: JJM
You know Tim, you happen to have a good point. What's going on, they all seem to have very high low side readings??? Part of it seems to be a lot of the silly kit usage, but even those who are performing proper repairs seem to be running into the same issues.


When considering your next auto A/C purchase, please consider the site that supports you:

My guess is too much oil. Can't say for certain but that' my outside looking in guess. Might be good to also check the purity level of the current refrigerant on the market.

When considering your next auto A/C purchase, please consider the site that supports you:

Cussboy on Tue August 16, 2011 4:30 PM User is offline

Sounds like it was overcharged before. I don't know if you should do anything about the oil loss. It's very tough to judge, and who even knows if the correct amount of oil was in there to begin with?

Cussboy on Tue August 16, 2011 4:30 PM User is offline

See above.

Edited: Tue August 16, 2011 at 4:31 PM by Cussboy

Spikepaga on Tue August 16, 2011 5:18 PM User is offlineView users profile

I am scared to mess with it since its doing so much better now. Yesterday after the "incident", at 7pm in at least at 90 degrees it was doing much better than the way its been performing at 10.30 pm in the low 80's. It was actually freezing.

I guess the question would be if your low side was open at full blast for 30-50 seconds spewing oily foamy gas out, would you add oil to it? The stuff that came out was pretty oily.

I guess I should have the system flushed..again..... :-(

I know that a parallel flow condenser can not be flushed after a failure, but can it be flushed from just oil by a regular mechanic?.

Just want to make sure that if I take it in I start from scratch.

This whole playing with freon and gauges has clearly been a misadventure for me.

NickD on Tue August 16, 2011 5:24 PM User is offline

Working in the field of electronics or even AC, I am no better than my test equipment, all of it has to be traceable to the NTIS. And for me, that includes my AC manifold gauges, have a several NTIS standard gauges to compare them against. Guess I have never seen a high side gauge set without a valve on it. I did test one of those low side kit gauges, was 20 psi off at 30 psi, it only showed 10 psi!

That is criminal to say the least, everyone would be overcharging their low side by 20 psi! And heaven help the high side. Your high side is way too high, but is that actual or is this what your gauge is saying? See Tim about getting a good set of Mastercool gauges.

Could use NAPA brand lacquer thinner to flush out your evaporate, TXV, condenser, and hoses, it real lacquer, not that crap they sell at hardware stores. I am thinking you have a TXV system, you will have to replace your receiver as the desiccant is already shot. It can't be exposed to moisture. Compressor will have to be drained and flush out with new oil, then drained again. I prefer injecting PAG, because that is the way the OE's do it after drawing a deep vacuum. Adding the oil in the proper quantity is the only way to be assured its correct. Yeah, I like the old York system with an oil sight glass.

If you have too little oil, your compressor will seize and you will have to replace your parallel flow condenser. Too much, may liquid lock your compressor and have the same problems.

Where is Chick at? Do it once by doing it right the first time.

Edited: Tue August 16, 2011 at 5:44 PM by NickD

Spikepaga on Tue August 16, 2011 6:56 PM User is offlineView users profile

Nick, thanks again.

Well, I did do it right, at least in the beginning (I hope):

#1-Last month when the new OEM compressor, parallel flow condensor, new exp valve and dryer where installed, the system was flushed properly and my mechanic (who is pretty good on these Jags) assured me that the correct amount of oil was in.

#2-Fast forward to 6 days ago...I was unhappy with the cooling so I add what I think is half of a 12oz can of R134 without oil using a cheap recharge gauge. Like 8 or 10 oz. Pressures get high compressor starts cycling, I start purging freon by pressing on the low port valve until the compressor stops cycling.

#3-Yesterday I get gauges and accidentally blow freon and oily foam for about 30 seconds from low side. Performance increases dramatically. Actually it's doing its best since bringing it from the shop from number 1.

As you can imagine I would hate to go back to get work I just had done a month ago because of all this, but I will if I must ,I just wont be able to do it for about 20 days

Please answer this hypothetical question: If you have a system that has the correct amount of oil in it, and the low side is open blowing gas and foamy oil out of it for one minute would you add oil back to it if you could not have it evacuated and flushed and how much??

Clearly I am not interested in adding refrigerant since it seems to be performing much better.

Thanks for bearing with me

NickD on Tue August 16, 2011 10:31 PM User is offline

Lets just talk about step one, if you have a good Jag mechanic, and were not satisfied with the performance, why didn't you just take your car back to him and have him correct the problem.

Instead of steps 2 and 3, where from what you said, you messed it up.

Somehow I got the feeling, your mechanic did not do this work for free. Does he guarantee his work?

JJM on Tue August 16, 2011 11:29 PM User is offline

It appears this system was never charged to spec - otherwise it wouldn't be cooling so much better now.

At this point, I would make sure the correct charge is weighed in. The system might be performing properly now, with the lesser charge masking a problem, but an insufficient charge can also lead to lack of lubrication and compressor failure down the road.

As for the oil loss, how much do you think you mopped up? Low side, it was probably less than an ounce, so I would say add a 1/2 an ounce. If your windshield was heavily coated, you might want to add an ounce. Of course, the only way to know for sure is start with a dry system.


When considering your next auto A/C purchase, please consider the site that supports you:

Spikepaga on Wed August 17, 2011 6:59 AM User is offlineView users profile

Thanks for your replies.

Nick you are correct, the labor was was not free, and I would not feel comfortable going back my mechanic to request his work guaranteed after playing a/c guy (as its so well illustrated in this thread)

I will end up going back, just not for about a month maybe longer if the car keeps on cooling as good as it has, and I expect to have to pay for a new drier, exp valve and his labor to evacuate, flush and recharge the system.

Edited: Wed August 17, 2011 at 7:16 AM by Spikepaga

Spikepaga on Wed August 17, 2011 7:49 AM User is offlineView users profile

Joe thank you as well.

The Jaguar XJS (the sports car 1976-1996, not the saloons) pretty much looked the same for 20 years and although they were offered with different powertrains thru its life, one of the systems that remained stuck in the early 70's (maybe even late 60s) is the A/C, according to most owners. During 1995 and 1996, the last two years of production, the car went to r-134, but the serpentine condenser was retained.

It is a well known fact amongst owners that it is very difficult to get the air conditioning "right" and sometimes a bit less is more productive and there are other reports that a little more can also help. Hence my adventures into air conditioning systems

I was certain that the parallel flow condenser with 2 Spal 9' pusher fans in front would decrease vent temps by several degrees, but clearly that did not happen. I am not sure if because of the parallel flow condenser was installed there should have been less refrigerant than what the factory specified or not.

So that I can call it a day until I go back to the professional to look at it; with this manifold set I have, how do I add 1/2 oz or 1 oz of oil into the system??. I think that sounds very fitting considering I was puging refrigerant for 30 to 50 seconds. I also thing that if the system was full, surely I could not have undercharged it by much, specially seeing how well it appears to be doing. There is no doubt that there has been a great improvement.

I typically throw parts at my car when something goes wrong, so I do have a new high/low pressure switch and evaporator temperature switch that will probably require the system to be evacuated to be installed. This is why I am trying to avoid going back to the shop at the moment. I would like for it to get evacuated and flushed once I recieve the before-mentioned switches and once I purchase a new drier and expansion valve. Although the latter two are very inexpensive, I really can not squander any more this moment.

#1-On a stock r-134 that came with a serpentine condenser, should the charge be a bit less than factory spec??
#2-Will I be able to have the new parallel flow condenser flushed from oil..I know its recommended to replace on the event of a failure, but if I just want to have it flushed to make sure I have the correct amount of oil in there, is that possible?
#3-Can I get a bigger expansion valve and will that help?-I have heard of people doing this, but am not sure if it is true?

Thank you very much. I am sorry I keep on asking questions, I do not mean to treat you like a concierge service, I just do not know.

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