I generally agree and just trying to help a friend that has a problem with a car they bought on the cheap. I was more or less asking a question of a curious nature if you knew at an estimated point where the high pressure switch might kick in. I think the system would first just not cool effectively when too much Freon is in the system, but at some point the pressure would be too high and the switch would just cutoff the compressor for protection. It is more of technical issue and probably related to psi vs amount, but there is some sort of relationship between the 2.

I have the proper vacuum and weighing is a simple manner.

Beyond needing a new compressor (under warranty) the only problem I have ever had with mine is the high pressure shrader valve seems to be a weak link and does not like to close easily once pierced. The first time I used it before getting a new compressor, it would not close back at all and had a substantial leak. I replaced it, but on the friend's car i was helping with, the same thing happen and I am using standard quick connect hoses that are very normal- much like what Rick showed in his photos and I have another friend that experienced the exact same problem on a 2000 XKR.


So just a warning to DIY- sometimes a shrader valve that has not been pierced before or has had years since it was, make sure to check for leaks/
after pressurizing. Before the job, I might well get a new set. This is what they are and Rock auto also has the same at about the same price https://www.amazon.com/Four-Seasons-...ype=automotive

Tom in Dallas/Plano

 

Thanks for your posts !
Question
Are your pressure readings at idle? And are you getting those temps at idle. I have serviced my twice now and cannot achieve the same results.

However, when the car is driving or the RPMs are up the temperature drops right down.
Bad compressor ya think?

 

Oh ya... Im getting the same readings pressure you are?

 

JaguarEnthusiast, it would really help us to help you if we knew what Model Year and engine you are inquiring about.

 

Rick,

Thanks MUCH for the great thread. Did the compressor change this morning (car had 194,000 and original compressor) and at idle its blowing 37 degrees out the outlets!!

Signed very happy in Arizona!

Joe A

 

For what its worth, I hook the gauges up to the car first then hook the vac pump to the yellow line, open the low (blue) side valve and let it pull vacuum for the described 45 min. then close the valve on the gauges and let it sit, and make sure it holds a vacuum on the gauges. This will keep you from wasting the Freon on a system with a leak. Also if you are pulling a vacuum for 45 mins you are going to need to add oil back into the system.

 

We do the same thing and if its at home or the end of the day, close the taps on the gauges and let it sit over-night. Next morning if you still have a good vacuum in the system then its secure and ready for gas.

 

Rick,
After evacuating the system should I add some oil before charging?

Howard

 

Howard, I have evacuated 4- S Type systems, among other marque vehicles. One as recently as 2 weeks ago in what used to be Jon89's 2005 S Type. The new owner and I did the plunger/spring reversal.

I have never added any external oil other than what comes in the refrigerate cans to charge the systems. I hope this answers your question.

 

Hi Howard,

The short answer to your question is, "Probably."

But the answer depends on the work that was done prior to evacuating the system. Was the compressor replaced? Condenser? Receiver-dryer? There are general rules-of-thumb for how much oil to add depending on which components were replaced. You can find guidelines with a little online research.

If the compressor failed internally and was replaced, other components like the condenser, receiver-dryer, and expansion valve should also be replaced, and the remaining hoses and evaporator should be flushed with an appropriate chemical to remove any seal material and other contamination from the failing compressor. To determine how much oil to add for a new compressor, you drain the oil from the old compressor, measure its volume, drain the oil from the new compressor, then add back the same volume of new oil as was drained from the old compressor.

The A/C specifications for your car will give a weight of R134a refrigerant the system should be charged with (typically in pounds, ounces, or grams) and the volume of oil to add (typically in ounces).

If your system was leaking, it has lost some of its oil as well as refrigerant. If your system was not leaking but the compressor clutch failed, you only need to be concerned with adding enough oil for the new compressor (per the method above).

Over-filling the system with oil will affect the system's ability to cool and can lead to excessive system pressures and other issues. Under-filling can cause insufficient compression due to reduced sealing, compressor overheating, and premature compressor failure.

Let us know what service was done prior to the evacuation and we'll try to help.

Cheers,

Don

 

If you do not know what Rick was talk about with the valve - here is the TSB: http://www.jagrepair.com/images/TSB/TSB2/X-Type/412HVAC/JTB00183NAS1[1].pdf

TBB

 

Rick,
Thank you for that information. I have read about the plunger/spring reversal but it is not clear to me if the spring is removed or if a different spring is substituted. If a new spring is needed where can I purchase one?

Thanks,
Howard

 

You are just reversing out the existing spring and the valve.

TBB

 

Tom is correct. You remove black cover plate, pull plunger straight out then remove spring. To assemble put plunger in the way it was removed, put spring in the bolt black cover plate back on, it's that simple!

 

Make sure to replace with new o-rings any that you remove.

TBB

 

Thanks Rick. I totally understand now.

Howard

 

Yes, I have already ordered a new O ring.

Howard

 

A little bump to this very helpful thread. Be aware new refrigerant cans now have a different neck with a self-sealing valve. This requires a new type of can tap.

The old style pierced the solid metal end of the can. Once pierced, if you didn't finish off a can, the remaining contents would escape when you removed the tap.

The new style of can has a spring-loaded self-sealing valve. It's now possible to save a partially-used can. However, the old style can tap doesn't work on the new cans. I recommend a MasterCool 85512, available from many online sources:

https://www.mastercool.com/product/r...can-tap-valve/

Other companies sell similar can taps, but reviews are all over the place. The Mastercool version lets you fully thread the tap onto the can before extending the plunger to open the valve. Some other brands have a fixed plunger that opens the can before you finish threading the tap in place, leading to potential leakage.

 

Karl,

Thank you for this important update!

Just to elaborate on the difference between the new tap valves and the old ones, the new ones have a blunt tip to depress the rubber seal on the new self-sealing cans. The old tap valves have a sharp needle point to pierce the metal seal on the old cans. Not only will the sharp point not properly depress the rubber seal on the new cans, it will puncture it and possibly cause it to leak once the tap is removed. Don't ask me how I know.

Ditto on the Mastercool tap valve with the large round lugged "faucet" knob. I have not had good luck with the Interdynamics brand tap valves with tee knobs sold at O'Reilly and elsewhere.

Cheers,

Don