~~~~ Please skip forward to the fourth entry that starts off 'Here's the update...' ~~~~







Check that...temp control lever seems to be working now. Not sure how that mis-observation was made but I'm going to consider it an anomaly, or maybe just my bad...dunno.

So the updated info is that now the '96 XJ 4.0 has what seems to be only an a/c problem. Engine changes idle speed when the a/c is turned on so I'm assuming the compressor is trying to work.

After the a/c ran for 10 min both lines leading from the compressor were warm.

Next step I suppose would be to check a/c system pressurization. My experience with a/c systems losing pressure in the past resulted in a slow loss of cool air where it gets less and less cool until the air finally isn't cool at all...which coincides with the 'freon' slowly leaking out. Since this happened all at once should I assume there's a major leak somewhere and should do some kind of system pressurization test before I dump more freon in? Or should I be looking somewhere else in addition to checking freon?

 

bump

 

http://www.naxja.org/forum/showthread.php?t=1120851

Have you put gauges on it yet?

 

Here's the update...

(Please ignore the title of this thread...only problem I'm having is with the a/c now)

Knowing very little about A/C systems I assumed as I'm blowing warm air with the a/c on that my refrigerant had leaked out. Well I got a can of refrigerant from the parts store and hooked just the gauge up to find that actually it seems my refrigerant system is OVER pressurized. Now how'd that happen!? Also, my serpentine belt just started to squeak. Never has before and seems tight, so dunno maybe the two problems are related.

Anyone have advice on where to look for the problem with this new info in mind?

(Thanks for the help md, I'm all ears.)

 

Was the compressor engaged when you checked the pressure. Was the AC clutch engaging?

 

You have a valve(hovers roughly 8" above your distributor) that controls flow to your heater core, a vacuum line closes this when the AC is on. This line is plastic & prone to breaking, check to make sure this isn't the case. If this valve is open, you'll be running heat while using the AC, and you'll also have a small vacuum leak.

When this happens the AC will work fine in the morning when the engine is cold, then go warm when the engine reaches operating temp.

 

Actually, the heater valve can be eliminated with no such consequences. The heat is controlled by a blend air door which is cable operated.

Thanks to djb383 for this:

One thing you may want to consider is removing/eliminating the heater control valve, if you haven't already. '96 down have the HCV, '97 up the Factory eliminated it.

During the warm months, with a HCV, (temp lever/**** never moved off cold) coolant sits and stagnates inside the heater core.....There's no fresh coolant/corrosion protection circulation through the heater core.

With the HCV removed/eliminated, coolant/corrosion protection flows through the heater core constantly when the motor is running, regardless of where the temp lever/**** is set.

Also, you don't have to remember to turn/slide the heat lever/**** when flushing/re-filling the cooling system because coolant is flowing to/through the heater core when the motor is running and the HCV is absent.

Be sure to plug/cap the small vacuum hose when eliminating the HCV.

 

jp I'm not sure how to tell if the compressor clutch is engaged by watching it. If you can tell me I'll redo the pressure check. I take it I should take the reading when the compressor clutch is engaged?

Twisted I haven't noticed the a/c being cold right at engine start (or at all really) but I haven't been paying that close attention either. I'll make sure to run the a/c first thing on next start up and see.

 

Look at the compressor. Is just the outside of it spinning with the belt or is the center spinning also?

 

Thats the compressor. The round thing on the front with the three circles on it is the clutch. With the AC on it is supposed to be engaged which then spins the compressor. Turn your AC on with the engine running and see if it moves.

 

Thanks jp, TWisted, and cruiser.

It seems my compressor isn't engaging at all. Started the engine, turned the a/c on and observed a stationary compressor wheel for at least 15 minutes, while alternating the controls between max, normal, and bi-level. Also the squeak that just started (which I assumed was the serp belt) seems to start right when I turn the a/c on. And although its hard to pinpoint where a squeak comes from I'm fairly sure its coming right from the compressor.

When I did the pressure check using the gauge on the refrigerant can before (and again just now) the pressure reads a steady 120 lbs for the 5 minutes I left the gauge hooked up, again with the a/c on but nothing turning on the compressor.

What more should I do to confirm that this is def a compressor clutch problem? With what I'm seeing could it be anything else?

TWisted I checked about that potential problem you mentioned. Turned the a/c on right at starting the engine and nothing but warm air blew out.

 

Did you do this with a warm or cold engine bay?

 

Have you checked the relay for the AC clutch? Also if that squeal is coming from inside the compressor housing it could be the bearing inside. Some guys have threads rehabbing the bearing, El Guapo has a lot of stuff on it posted. Remanned compressors online seem to be about 200 bucks.

 

jp, I would say the engine bay was cold. First start of the day at about 75 deg outside. After start up I turned the a/c on and watched the compressor from there. Said I watched it for 15 min earlier but it might have actually been closer to 10. Either way it never budged. By the time I turned everything off the motor had heated everything in there up pretty good.

Although I have a multi and know how to use it somewhat I'm not that knowledgeable at testing and would have to be walked through it. I do have a FSM so that that'd probably be a good place to start. Since this squeak really does seem to be coming from the compressor I'm gonna start there and see what I can do.

Been told that when I get the belt off I should try to turn the compressor. If it doesn't turn then there's the problem.

So if the compressor doesn't turn, should I replace it and use the old clutch. Or should I just replace both at the same time.

And if the compressor does turn, should I assume the problems with the clutch and just replace it and use the old compressor, reinstall and see what happens?