Hi everyone - 2000 Jaguar S Type - 4.0 V8 - I checked my AC pressures today with my manifold gauges (80 degrees ambient temp outisde) - Low Side between 46 - 49 PSI and High Side - 175 PSI - I believe these pressures are good.

Here's the kicker - the air blows cool (55 - 60 degrees) at idle but when the car starts moving the air coming out of the vents blows significantally cooler (40 - 48 degrees) - is this normal?

As far as the compressor is concerned - I saw some accumulation of fluid under the compressor pulley but not sure if that was freon residue or not. I wiped it off and tightened the 3 - 10mm bolts at the front of the compressor.

Any feedback would be greatly appreciated. Thanks!

 

Just taking a stab here, I would say that you should start by getting an evac and recharge on the system and recheck performance of the a/c. As for the oil spot's sounds like the front seal may be on the way out. Was the oil residue either green or have a rather unpleasant smell ?

 

The compressors on these cars are subject to failure, particularly if you are seeing the build-up of green residue on the compressor's underside. That's the dye in your R-134a. Classic signs of a leak leading up to a gradually dying compressor....

 

Thanks for the responses guys - I was back under the car this afternoon and sure enough - the accumulation of the R134A w/dye is right in front of the compressor - same spot where it was yesterday. Time for a new compressor I guess.

Take Care!

 

The residue had a green tinge - dye from the R134A

 

When our S-Type's factory compressor began to fade away in May 2010, it sounded normal even when I was underneath the car with the engine running and HVAC system running on high. But when I placed the tip of my mechanic's stethoscope on the compressor's casing, it sounded like a full-blown cement mixer inside. That's what ultimately convinced me that the compressor was indeed on its way out. We did not have the usual dye leak / green slime build-up, so it took me a week or so to finally figure out the problem....

 

Be sure and source the Lincoln LS part from EBay or RockAuto or maybe Amazon. Good bit cheaper.
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I have a 2000 S-Type 3.0. I had a small green dye leak under my compressor. I traced it to the low side schrader valve area (near the compressor) and took off the cap. The leak was coming through a defective schrader valve core. I had the core replaced and re-charged the system and it has worked fine for over 6 months, even though the A/C mechanic told me the compressor was going out. Just suggesting to check the cheap simple things first before replacing a compressor. If the leak is actually coming out of a compressor seal, then I guess a compressor replacement is called for.

Good Luck!

 

It's funny - I thought the same about the schrader valve, considering whomever worked on the AC system last lost the low side cap - (just recently ordered a replacement and installed the other day) - unfortunately, for me the leak is coming from the front seal - I went under there with the UV light and sure enough - I traced the leak to the front seal on the compressor - thanks!

 

UPDATE - So I finally had a new Motorcraft compressor and dryer (purchased from XJR93-S here on the forum - thanks!) installed this week by my local indy. Picked up the car yesterday and asked some questions after my mechanic started acting fuzzy about the amount of 134a freon charge put into the system.

The mechanic stated he "just charged the system enough to get the clutch to kick on"....he re-gassed the system with only 1.50 lbs of 134a which he claims is what the system calls for - that sounded a bit low for me based on what I read here on the forum. There is no difference in air temperature with the A/C on...

Sure enough JTIS calls for a charge of 800 grams of 134a (1.76 lbs) and 7 oz oil (I know the new compressor already had oil in it) - Needless to say the car will be heading back to the mechanic and I am tempted to tell him to perform a full recovery/evac and re-charge of 134a and oil.

Anything I missed?

 

Not good! Any beginner A/C guy should know you must fully evacuate the system and then hold that vacuum for at least 30 minutes. I always hold it over night or longer and then vac it down another 30 minutes or so. The more time you spend on this the more moisture you get out and the better the system will cool. Commercial shops are under too much of a time strain to do this and that's one reason I started doing my own A/C work besides the tremendous cost savings.

I always weigh the amount of R134a put in the system. It's not hard when using the small consumer type freon cans. If it's a real A/C shop they will have a charging scale and can put the correct amount in down to the ounce. I can get very close with my postal scale at home.

How much oil did he put in the compressor?

The receiver/dryer should also have several ounces of oil put in it. The yellow/green stain you see is not from the refrigerant but from the oil in the system. The oil is clear when new but like most fluids when used it picks dirt and changes color with age. You see it on the compressor because that is the lowest point in the system and gravity makes the oil pool inside the compressor when the system is not running. So the system pressure will push on the oil and if you have a leak in the compressor/front seal the oil leaks first. This is why it's an early warning sign. It will eventually push so much oil out that the compressor will eat itself internally and spread "Black Death" thru out the system making for a much more expensive and difficult repair.

I always put the 3-4 oz of oil in the compressor and then turn it by hand until the oil is spread around inside the compressor. Then I set the compressor clutch face down for at least 30 minutes. This is not required but I do it to make sure the front seal is well lubricated when the clutch is first engaged.
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