I took my 95 VDP/AJ6 into the shop to get the AC checked . Outside temp 85F high humidity. They put the gauges on, low side read 93, high side 90 (car not running). Car running ac on, low 85 high 90. No visible leaks, compressor running okay. The car wouldn't take any 134A gas when they tried adding some to the low side. Any guesses? Thanks

 

Sorry no replies until now, I just saw this. Sounds like it is holding some charge, but the compressor isn't doing anything. Not surprising it wouldn't take any more 134A, there's not low enough pressure to suck any more in. I am surprised they attempted at all. What next, did they diagnose as compressor failed? And are you certain the compressor was actually engaged?

 

Hello Rich, the compressor's been leaking Pag oil (very little) for some time now and yes it does still engages. This just gave me incentive along with the fact it didn't implode yet to get a new one along with the condenser & dryer. As said, my main concern was changing the expansion valve, I'm not tearing into the dash to replace it. That's one nice thing about the xj-s v12, the expansion valve is in the engine compartment.

I'll post results later

 

To know if the compressor is spinning after clutch engagement would be the temp difference in the lines other then the sound or by feel vibrations . The compressor can be removed and disassembled pretty easily in the linked video from the vendor in the video along with their parts . Your compressor is a Denso 10PA - 17C .


https://www.shopcenturyautoair.com/s..._Products.html

The compressor clutch can be removed without the compressor removal from what I understand .

Expansion valve from what I have heard from Motercarman can be blown out with compressed air from both sides negating a need for replacement . The most common cause for this blockage is the releasing of the particles the dryer ( $ 35 ) which don't last forever .

You would have to map out your strategy in what you want to address as you have to charge it back up if you address one item at a time .

So my recommendation would be to remove the compressor and overhaul the compressor yourself and you can see if the piston rods had been damaged by the loose particals from the dryer . Replace the dryer and blow out the expansion valve several times from each direction ..

This DIY approach will save you alot of money

The compressor nut can be impact wrenched off a a local shop and I think it was a 10 mm so you may have to provide the socket

the car is serviceable with that one belt off and there are some tricks to the loosening up of the belt tensioner and pulley which are about $ 13 .

The X300 series air conditioning starts on page 83 of the 703 doc .

Editing

 

I think the compressor is dead because the gauges didn't indicate a blockage situation. If there is no debris in the hoses from a split dryer, no need to go after the expansion valve other than a blow-thru (I think in the "backwards" direction would be prudent). Parker, would a compressor "reseal" bring it back to life?

The spec for the PAG oil is "ND Oil 8" which I found thru research for my project last year, is PAG 46 oil. A new compressor will have some oil in it already, but look for which kind. There's a method to calculate the amount of oil to add, guidance that should be included with the compressor. All stuff a technician would be very familiar with.

"1100g" of R-134A which is about 39 oz.

Funny to hear of one item that is easier to replace on an XJ-S compared to an X300!

 

I agree, (and hope) the compressor is shot. Rebuilding it a cheaper option but for around $250 new ones are available & I don't need the aggravation of something going wrong via a rebuild. Wonder why Jaguar doesn't use a orifice tube somewhere in their system? The new compressor came with shipping oil. I'll drain it & fill with right amount of pag46

Yes all (1991 @ least) XJ-S V12 ac components, except the evaporator are "pretty easy" to access once the hood is off. Big plus is no under car work.

 

When I received my M'Lady P I knew it had been wrecked on the front left side . The sheet metal and paint was somewhat correctly done but unknown to me was the front condenser was punctured and reinstalled . So I remove the the whole tubing and compressor to do a complete overhaul of the system . The compressor removal was not bad on the X300 .

The mystery of no pressure ( or temps ) between the high and low lines on your example could be explained by a non rotating compressor or mechanically broken internals ( from the dryer particles ? ). Since you already have a replacement compressor in hand ( I thought they run about $ 400 US and above ) a cheaper seal replacement step can be skipped .I'm assuming you are replacing the compressor clutch at the same time to cover that suspect .

Motorcarman ( Bob ) from his many experiences recommended blowing the XPV in both directions and if I remember correctly never had to dig out the XPV for replacement . I personally am considering putting some heat and cold on the bulb of the XPV in order to exercise it open and closed to work out any binding particle while blowing through . Easier said then done before executing this .

You may have a second issue with the servicing port being clogged or stuck .

When you get back operating the was a TSB on a jumper plug bypassing the 2 wire low pressure switch based on their in service unreliability so you would have 2 modes of operation on the radiator / condenser fan operation that does have a effect on your AC performance . Without the simple to do modification by turning on the AC the unreliable 2 wire low pressure switch should turn on one fan . With the mod one fan will always run regardless of whether you have the AC on of off . The high pressure 2 fan operation happens when the 4 wire pressure switch closes The other set of 2 wires in this 4 wire switch disengage the compressor in a AC system over pressure situation .To test just put a paper clip in the connector between on of the colored wires and one of the black wires . This will give you either 2 fan operation or compressor shutdown . Low current control circuit so no harm done .

 

Also, please replace the valve ports while you can. Easy and inexpensive. They are threaded on, GM type ball valves. Be careful not to stress the aluminum fittings too much.

 

Thanks Richard, great advise. I was watching "Eric the car guy" on UTube a while back & he mentioned the high percentage of leaks that came from those ports. I make it a point to change them when ever the system is down. I didn't know they were just standard GM though.
Larry