Hello fellas,

1999 Cherokee Classic, 4.0L, 6cyl

The A/C has been blowing cold only when idle, as soon as I start driving or revving up above 1.500 RPM, the a/c compressor starts "growling" and eventually shuts off... thus no cold air. As soon as I pull over or stop at a light, it's ice cold again. Orifice tube gets ice cold and stays that way.

There are no leaks in the system, it's been vacuum tested and everything.
Low side pressure reads about 30 PSI on a 90 degree day (slightly lower than I expected). However, if I try to add even just a very little bit of freon, the compressor will spit it out the back through its relief valve as soon as I rev the engine up a little. I think it's building up too much pressure on the high pressure side of the compressor.
It basically sounds and behaves as if it was overcharged (but it's not).

Any thoughts on what could be causing this?
Again, keep in mind the air blows nice and cold with the engine idleing

Thanks

 

UPDATE:

The more I think about it, the more I lean toward a stuck expansion valve.
I mean, if it was a blockage causing too much pressure on the High end it wouldn't matter if the engine is idling or cruising, it just wouldn't work at all, right?
A stuck/broken expansion valve however *would* allow the A/C to work fine as long as the system pressures are compatible with whatever position the valve is stuck on (idle pressures, in my case), but stop the system from working as soon as those pressures change too much.

Does it make sense or am I way off?


(edit)
This may also explain why the A/C does kind of work when I am driving as long as I keep the A/C fan on -1- (lowest) and it's not too hot outside.
I said it "kind of works" because in Texas, with 100+ degrees temperatures regularly, it's pointless to have cool air barely seeping out of the vents... When it's set on -1- it can't be hotter than 80 degrees out for me to feel any difference in temperature inside the car

 

...nothing?

 

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