I've repaired and recharged a lot of a/c systems but never had the problem I ran into today with my 02 expy 4.6. I noticed my air wasn't quite as cold as it used to be. I replaced the compressor, drier, expansion valve, and condenser about a year ago. My air has been frigid ever since except lately. So I look at the high side valve and I can see small bubbles forming indicating a leak. I evacuate the system, replace the valve, and begin to recharge after a full vacuum down to about 29. Part of the first can goes in and I start her up. No compressor engaging at all until I open the high side of my gauges and let some of the pressure to the high side. Compressor then starts to cycle on its own for very short cycles. After a few minutes there has been no change at all in pressures. Low side sitting at 75-80psi and high side cycling between 50 and 80 with the compressor. Long story short I jump the relay to have continual compressor clutch and the low side never goes below 75psi??!! I get the high side up to about 125 with the second can but after about half of the second can, nothing is happening at all anymore. No pressure change on either side with continual compressor engagement. The can is warm signifying a high pressure so I know the gauge is accurate. And freon has stopped entering the system. Is it just my compressor is bad already? A bad expansion block? Climate controls set at max a/c the whole time. Please help!

 

Update: this morning I checked pressures again and they had equalized at about 65psi. Engine running a/c on, high side cycles between 80 and 100 while low side does absolutely nothing. I mean no change in pressure at all. No up and down, no cycling period. Set at about 75 and stayed never moved an inch. Does the compressor have valves inside that could be stuck? There is no suction being created at all. I'm gonna go ahead and change the compressor if I don't get any answers. Hope I'm not wasting my money! I can't imagine what else the problem could be.

 

I have this same issue with my 2000 Jaguar S-type (clone of Lincoln LS)
AC compressor is high on low side and high side won't go up any further (will not accept any refrigerant) I thought it was the control valve but it turns out to be a gasket/seal leak in the compressor. The leak showed itself after a week of use, is it still cooling a little bit or not activating at all?

If it doesn't hold vacuum for an hour, I'd check for leaks.



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Thanks for the input...its not leaking. The air was still pretty cold before I did any of this just not as cold at idle as it used to be. It had a very slight leak at the high side valve but that's it. I'm stumped because if my compressor had failed like that it wouldn't have been cold before either. I think I'll check the orifice tube and make sure it's clear. I've made a video to show what it's doing. Please check it out and let me know what any of you think. Compressor? Expansion block in the rear? Orifice tube in front? Demon possession? Thanks for any and all input.

https://youtu.be/RJMC4hOY3Qc

 

Here's another short video showing exactly what happens with the pressures when I manually cycle the compressor.

https://youtu.be/sGfP6u_Gh6c

 

To get the pressure/suction you need a pump and a restriction. The compressor is your pump and the expansion tube is your restriction. Is the hose getting hot on the discharge side of the compressor? Any cooling of the hose past the expansion valve?
My guess would be the compressor, but the expansion tube is easier to check and cheap to replace.

 

If the compressor is cycling on its own (unclear from your description of the current condition) OR if there is some cooling but the low side gauge isn't moving, the problem isn't the system, its the gauge or its connection into the system.

Suggest you make necessary checks to affirm your confidence in your test equipment before returning to the vehicle.

 

The compressor does cycle on it's own. No there is no cooling at all...none of the lines...but keep in mind everything I've shown up to this point is happening when adding the FIRST can! Which should get sucked right in within a minute or so. It calls for 5 cans. I haven't even been able to add 2. I've visually inspected the orifice tube and expansion block in the rear. All seems fine, no restrictions, I'm able to blow through the orifice tube a tiny bit which is normal. I'm confident that the gauges are accurate since I used two different gauges and got the same readings. Also the symptoms match the pressures...the can is warm, indicating a high pressure and it's not being emptied at all. The compressor seems to max out at about 125 on the high side. I let it cycle for 30 minutes yesterday and it never climbed higher than 125psi.

I've ordered my new compressor and component kit to do it all again. This time I got the scroll type which is the OE design. Hopefully this one holds up longer. My warranty on the other one ran out the 6th of this month!

thanks again guys! I'll update soon with the results

 

Do you have the high-side manifold valve open while the system is trying to run? If so, that's a pretty good way to turn the can into a hand grenade.... and is something that should never be done. It also screws up the charging process....

 

very true! Thankfully I learned that a long time ago. Definitely had the high side closed the entire time.

 

yep, definitely time for a new compressor if your gauges are installed correctly.

 

It's fixed! New compressor and drier and its like new again. Ice cold. Thanks for the input guys!

'til next time....