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Air Cond gremlins, need help!

4

4x4xj89

NAXJA Forum User
Location
Texas
Guys please help me figure it out.

1989 XJ 4.0L AW4

The AC normally works great, cools very well. The issue I have is every now and then, it stops working, keep blowing regular air (I guess the compressor stops working) I switch it off and on again and it works normal again.

What can be the cause, do I need a new control switch or its something with ground?

Thanks

Vic
 
It could be the high or low side pressure switches cutting off the compressor.

Put it into fault mode--run it until it quits, then test the connector at the compressor, work back from there.

It could be a number of things and you don't want to try and shotgun your way to an answer.

Good luck.
 
Joe, I love your term "shotgun your way to an answer". Aptly describes what happens when posters say they fixed this or that symptom with this or that soluton, when indeed there needs to be some logical testing to determine the actual cause.. Will you allow me to use the new term freely?
 
Feel free, Pard.
 
In order to up-hold the time honored shotgun approach (what are ya Joe, a gun control commie?) they also do that just before the compressor dies. You'll know because they squeal like mad and freeze up. Hard on Serpentine belts. Usually happens miles from pavement where there will never be a cell phone signal. Generally pulls your attention away from the pretty scenery.

Not saying you have this problem, but something else you can check.
 
Here is a thought, I know on other vehicles if the heater core is leaking at all they will freeze up and it will stop blowing cold, and if you turn it to vent and let it blow for a bit it will start blowing again. However if your compressor stops it may be a relay getting weak as well (not sure on the XJ).
 
97fordrunner said:
Here is a thought, I know on other vehicles if the heater core is leaking at all they will freeze up and it will stop blowing cold, and if you turn it to vent and let it blow for a bit it will start blowing again. However if your compressor stops it may be a relay getting weak as well (not sure on the XJ).
Click to expand...


In this case, when it stops working, all I do is turn it off and on and it's back to normal operating condition. I am suspecting a weak relay or as Joe said Hi/Lo pressure switch.

The compressor is fine, smooth, no noise, the belt is also in great shape no shiney spots.
 
cruiser54 said:
Joe, I love your term "shotgun your way to an answer". Aptly describes what happens when posters say they fixed this or that symptom with this or that soluton, when indeed there needs to be some logical testing to determine the actual cause.. Will you allow me to use the new term freely?
Click to expand...

Joe, let's add another catch phrase. How about "connections before components"?
 
MAX recirculates the air in teh cabin instead of NORMAL which sucks air from outside. Cold air from teh cabin being blown onto the evaporator will make it freeze up, thus blowing warm air. I would shut it off MAX after a couple minutes until im comfortable and switch it to NORMAL.
 
When you say you turn it off and on again, do you mean that you immediately turn it back on and it works or do you wait awhile and then turn it back on or what?

An improperly functioning a/c can freeze up. The evaporator coil under the dash will turn moist air into a solid block of ice which has to melt before air can once again flow through the coil and start the freezing process all over again. You will see posts suggesting that you do various things to prevent the freezing process such as not using the MAX setting or keeping a window open or not keeping a window open or whatnot in an attempt to balance moist air, warm air and a cold coil. These may help temporarily but understand that a properly functioning system will not freeze up.

Obviously, if you switch your system off and back on immediately and it works, freezing is not your problem.
 
Pelican said:
When you say you turn it off and on again, do you mean that you immediately turn it back on and it works or do you wait awhile and then turn it back on or what?

An improperly functioning a/c can freeze up. The evaporator coil under the dash will turn moist air into a solid block of ice which has to melt before air can once again flow through the coil and start the freezing process all over again. You will see posts suggesting that you do various things to prevent the freezing process such as not using the MAX setting or keeping a window open or not keeping a window open or whatnot in an attempt to balance moist air, warm air and a cold coil. These may help temporarily but understand that a properly functioning system will not freeze up.

Obviously, if you switch your system off and back on immediately and it works, freezing is not your problem.
Click to expand...

As you described, I just turn it off and immediately turn it on and it works just fine. I don't think freezing is the issue here, but I will check that possibility too.
 
sjx40250 said:
Did you check the gap on the AC clutch? When it gets to the outer limit of the gap range, the clutch will operate intermittently.
Click to expand...

I checked the gap and it seems fine. I have been running the AC full blast and I can't seem to duplicate the problem today.
 
Any big difference in ambient temperature/humidity? Keep some notes, post up if it reoccurs.
 
Well, it turned out to be the clutch, it was weak and sometimes not engaging. If I raced the engine a couple of times it would engage, or just touch it carfully while running with a screwdriver.
 
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