[zjosh93]

Sure sounds like clogged orifice tube to me. The orifice tube and the compressor are the gatekeepers between the high and low sides. It's taking 10-15 seconds for a 100 psi pressure differential to force a tiny amount of refrigerant through the orifice and bring the low side up enough to trigger the compressor. Once the compressor kicks on it sucks the low side down in half a second. On my 93 the compressor stays on pretty much constantly in the summer. Which is how it should be. Compressor short cycling is hard on the clutch.

FWIW any time you replace a compressor for mechanical damage (siezed) you pretty much have to replace the orifice tube, the accumulator (drier), and flush the lines. When I sold parts you'd see a lot of people buy just the compressor and then be back in 3 months with a dead compressor again, killed by trash the first one left in the system. Most compressor companies won't warranty a compressor unless you can prove you bought a new orifice tube or expansion valve, drier/accumulator, and a can of flush.

 

[zjosh93]

Good point Wingless. On the 4.0 the orifice tube is built into the low side hard line running from the condenser to the evaporator core along the passenger side of the engine compartment. Typically OEMs make the distance from the orifice to the evaporator core short so the gas doesn't heat up and large so the gas has somewhere to expand. Jeep for no good reason made the line narrow and long so it tends to pick up heat. You can make the AC work noticeably better by insulating that line.

https://www.rockauto.com/en/catalog/jeep,1995,grand+cherokee,4.0l+l6,1182103,heat+&+air+conditioning,a/c+refrigerant+hose,6900

RockAuto calls it the liquid line, even though there'd only be liquid in about 3" of that line, but sure. Cheap enough. It will be soft when you get it. Soft enough to bend it straight or make little adjustments here of there. It will eventually work hard as it temperature cycles.

 

[zjosh93]

Just buy real AC system flush:
https://www.amazon.com/Four-Seasons-69994-Super-Solvent/dp/B004AEQSE4

Most auto parts stores should rent the flush gun kit or at least they used to. The flush is designed to work with AC oil and lift contaminants out of the AC system.

Bad news is that some condensers and evaporators cannot be flushed. I'm not an AC expert. I think our ZJ evaporators can be flushed and the condensers can't be. But I'd defer to anyone with actual data. Or info from the FSM. I'd look but that PDF is on my other computer.