XJ Cherokee a/c issue

I thought i had this thing licked when i recharged it last week, but apparently not.

Symptoms:

A/C works for 10-15 minutes, perfectly cold, then starts to blow humid somewhat gross-smelling air, then ends up blowing warm. (Or at least outside temperature, no cooling effect.)

I have not checked for leaks, but my gut tells me that it's not leaking, as it's been performing like this since it was purchased almost 2 years ago, no better, no worse. Situation did not improve much with a recharge. (though it is a little colder now when it's working.)

I don't know enough about A/C to really figure this out on my own. Normally when it breaks, i just remove it.

Any ideas? I won't take it to a shop, not rich enough.

Sounds like an electrical issue. Almost like its on, but then it shuts itself off.

What do you have to do to get it working again?

The one reason it might shut itself off is when the refrigerant is still a little low.

Is it freezing up? Mine does the exact same thing because it freezes up and the temp sensor by the evaporator core shuts the AC system down until it thaws. Makes for a really nasty smell, too.

Nasty odor means water is backed up in the evaporator case. If it's deep enough, it'll freeze. Make sure the drain is open and flowing well. Otherwise, the symptoms sound like low refrigerant; A/C system pressures won't be correct without proper charge levels and the pressure switches will turn it off to prevent damage.

The other thing is the compressor clutch electromagnet coils will get weak, it will engage when cold but quit when it gets hot. If it quits cooling, the clutch is disengaged but there's power to the clutch coil, well time for a clutch coil, it's not terribly difficult and you don't have to discharge the system to do it, just have to lift the compressor up enough for the outer shoe to clear the radiator.

Thanks for the ideas, i'll poke around in there again when i get a chance.

Orrrr... nevermind. berkeleying truck just died anyways.

My XJ is parked right now, too. Too many problems have been popping up too rapidly for me to take care of them. I think that's the real issue with XJs, and that's that they tend to fall apart all at once. I've seen 3 of them do it, one of them my own.

For years we had a fleet of them at work for patrol cars and the AC almost always was broken on them. The few we had with power windows would also wait for the hottest part of summer and blow the window fuse as well to make the car an oven for 8 hours. Sadly they also ran forever so we have just finally retired our last one.

92CelicaHalfTrac wrote: Orrrr... nevermind. berkeleying truck just died anyways.

The crank position sensor is a common failure.

Curmudgeon wrote:

92CelicaHalfTrac wrote: Orrrr... nevermind. berkeleying truck just died anyways.

The crank position sensor is a common failure.

It would run perfectly as long as it had some throttle.

I messed around with some vacuum lines, since it wasn't throwing a code. I seem to have fixed it by accident. Runs fine now. Would a bad CPS let it run fine at any situation other than idle, though?

No, generally a CPS will kill it hot as in the engine will just shut off, it'll run again when it cools off. The TPS will cause all sorts of strangeness. I once saw a transmission replaced because of a bad TPS, that was embarrassing. Do the usual: replace every vacuum line you can get your hands on and make sure there's no bare or broken wires. Chrysler really cheaped out on the harnesses and they have been known to have insulation crumble due to heat/oil.

I kept thinking my xj (98) had a slow leak, kept re-charging every year. It would do the same; perfect for first 10-15 min then slowly die.

I hooked up some dual manifold gauges (HF clearance) and noted that I had OK low side pressure but had way to high high side pressure, meaning I have an occlusion,/ blocked expansion tube and not enough AC knowledge/motivation to fix.

Borrow a full gauge set; I recall reading that the expansion valve thingy is a common failure/gets clogged. Sorry I don't know more/understand it, but it sounds exactly like my xj.

One more suggestion on the AC: Check the clutch gap. If it's on the high side, the clutch may not engage when things get warmed up.

clutches tend to go bad. also the expansion valves are constant issues.... once it stops working hit the valve a couple times if it all of a sudden startes blowing cold again u found your problem.