2001 F250 SD 4WD, 5.4, extended cab, long bed

Trying to get to the bottom of my AC failure, and I have been around in circles a few times now:

Have charged the system once or twice over the years with the basic can and a hose deal. It recently was acting up so I went to do that again but according to the gauge on the hose it actually looked too high. OK, maybe its overcharged then? I let a little out but it didn't really change the behavior. Sometimes it would cool, sometimes it wouldn't. And it would magically change its mind when I stopped somewhere and started up again. (Intermittent issues, argh.)

So I decided to empty the system, vacuum it down and start over. I did that a couple nights ago, but it never kept running the compressor as I charged. It just kept short cycling. Eventually it wasn't engaging the clutch anymore at all, but I still needed about 500 grams more refrigerant per the sticker on the truck.

Maybe my pressure switches are bad eh?

Messed with those today. For a while, bypassing the low pressure switch at the drier would make the clutch engage, but again, it never STAYED on. That stopped working after a bit.

Eventually I bypassed both pressure switches and the clutch would then run steadily but I still wasn't getting cold air. At that point I had about 100psi on both low and high on my manifold gauges. I've had the low down in the correct range sometimes, but the High side never got above 100. I think it should hit 200 or more? Compressor clutch is engaged but compressor is not actually working? (And even that was inconsistent. At one point I went to show my neighbor it would kick on with both bypassed and...it didn't. Until 5 minutes later.)

Is the compressor dead? Time to replace the compressor, drier, evaporator and condenser? Is there anything else to check before I order a whole system worth of replacement components, any further adjustments or checks I can make on the compressor?

 

I just found a video showing it's possible for the outer part of the clutch to spin without the center actually engaged so I went to check for that.

The bolt head in the middle IS spinning so that was a dead end, but I noticed some noises which may be a clue:

I can hear clicking inside the drier that corresponds to the clutch turning on and off as well as some hissing. And I can feel flow through the thicker hose going to the compressor. Is there a valve in the drier? Is the click from the pressure switch? I don't really think its the latter because it doesn't feel like the click is that close to the switch body, but I'm still learning about the components here.

 

Got the compressor and the two lines that connect to it replaced yesterday before I ran out of time and had to go do other things.

Condenser, drier, evaporator, fluid line and both pressure sensors going in soon.

Look at that old orrifice tube…metal I expected, but hair??? What IS that?

 

I have the same symtoms on another vehicle.

been thru all the charge related items and I have all the tools and guages.

I replaced the temp/pressure switch and no improvement.

next on my list is to replace the txv.

if a txv replacement does not solve it...then the compressor will be replaced.
syst,.


but...usally a failed compressor also means compressor grit is in the condensor or evaporator so inpsection for compressor grit into the lines to determine if condesor/evatorator have compressor grit...not point putting a good compressor on a contaminated

 

that filter is likely the root of all your issues. if the compressor can't get a suction, it'll pull a lower pressure on the suction side. likely tripping the pressure switch. and if it isn't compressing, it isn't making pressure...so again explains the high pressure side being low.

my filter wasn't that bad, but it was fairly dirty when I pulled it out. picture doesn't really show, but almost all the mesh was blocked with some sort of weird material...and it was installed backwards.



Something else to check is the cleanliness of your evap core fins. Mine was absolutely covered with soot and dirt. virtually no airflow across it. until I cleaned it, my pressures were all over the place and was driving me crazy. pop the fan off, use a garden hose and degreaser to clean. the water will drain out the weep hole to the ground.

 

Cleaning, flushing, examining components is a non issue here: once I thought the compressor was an issue it made sense to change EVERYTHING.

Got the compressor in a couple days ago, put in the condenser and evaporator yesterday.

Maybe tomorrow I’ll have time to make the final
connections to the drier/accumulator and start the vacuum and fill process. I’ll report back when done with that.

 

Got around to charging late last night. Seemed to stop pulling refrigerant in at about 3 (12oz)cans worth, so probably got around 33-35oz of the 42 max into the system. Cooling pretty well, I think I saw it as low as 40 at one point, but definitely hitting about 45 degrees.

Wondering if I should try to get another half can in it, but I think its at about the right pressures. I found a nice chart today and will be checking it again soon.

Overall this project wasn't too bad. Way easier than manifold replacements lol!

 

Glad you got it working decently.
as far as the orifice tube...yours it the worst I've seen. I also don't understand how the various things get in them. I just replaced mine and it had a tiny leaf in it. the world of mysteries