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Old 08-27-2012, 02:02 PM   #1
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A/C Compressor will not engage

HiYa, all.... just picked up a '98 Wrangler, 2.5, 4cyl. auto. A/C compressor will not engage, so I did the following: #1, Tried to re-charge, the gauge went into the yellow area, border line red area. #2, checked the A/C relay, swapped them with the horn relay, both are good. #3, jumpered the low pressure switch with a paper clip, nothing. #4 un-plugged the connector wire (single black wire) going to the compressor and checked the A/C dash slide selector switches for recirc/fresh A/C and when switched, my test light indicated current from both positions and when switched to "off" current is off, so that is all working. #5, I noticed a black wire coming from behind the clutch and saw that it goes to the black wire I just tested for current and then doubles back to the side of the compressor and is grounded to the side of the unit with a phillips screw. It was rusty so I lubed it up and ALSO grounded that terminal to the neg. side of the battery and still nothing. The compressor does turn freely by hand so it is not burned up. Whats left to check? If the clutch is electrically shot and needs to be replaced, is it a simple fix? or does the system needs to be purged and be a major pain in da keester?

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Old 08-27-2012, 02:13 PM   #2
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If there is not enough freon in the system it will not engage the compressor and from the sound of what you say your gauge measured that may be the solution right there.

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Old 08-27-2012, 02:30 PM   #3
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Definitely sounds like the clutch. The clutch has to be removed with a puller and can be a major pain.
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Old 08-27-2012, 02:32 PM   #4
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But less a pain then a compressor swap. If you don't have a puller, you can borrow one from Auto Zone. Problem, I wouldn't buy any parts from there.
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Old 08-27-2012, 04:37 PM   #5
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Definitely sounds like the clutch. The clutch has to be removed with a puller and can be a major pain.
No, it sounds like it is low on freon. He needs to add some freon to the system while the engine is running so he can get some pressure in there to activate the clutch.
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Old 08-27-2012, 08:18 PM   #6
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I'm not here to argue, but if you read all the steps he made, he added freon. He checked the power and ground to the clutch assembly, which checked to good. Only two things left, one, he over charged the system and it's shutting down under protection; two, is clutch is bed and it needs to be replaced.
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Old 08-27-2012, 08:29 PM   #7
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It would not be bad to hook up a manifold gauge set to the system to get a full view. If you filled the system till the low side hit yellow, you had enough that should have engaged the clutch. I still believe, if you done all you stated, that you have a clutch issue.
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Old 08-28-2012, 08:44 AM   #8
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I'm not here to argue, but if you read all the steps he made, he added freon. He checked the power and ground to the clutch assembly, which checked to good. Only two things left, one, he over charged the system and it's shutting down under protection; two, is clutch is bed and it needs to be replaced.
After re reading this I stand corrected. I was under the impression that the gauge was reading too low on pressure which is why I made the suggestion I did. I now think it is over charged or as you say something else malfunctioning.
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Old 08-28-2012, 01:31 PM   #9
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Did you try jumping the 'high' pressure switch?
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Old 08-28-2012, 01:33 PM   #10
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I'm not sure you can add refrigerant without the compressor turning. If it's not turning you will get a real high reading on your pressure gauge.
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Old 08-28-2012, 02:22 PM   #11
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The A/C clutch is activated by a electrical coil, check between the hot and the ground wire and see if it is open, if it is replace the clutch assy.

BTW, you can not add refrigerant without the compressor working, the high side safety could be holding you out as well as stated above because the compressor is not moving the refrigerant through the system.

The compressor is nothing more than a pump, this isn't rocket science, the refrigerant changes state from a gas to liguid when it leaves the conderser coil, you do not want to pump liquid refrigerant through the compressor either (over charge), that will lock the bitch up real fast. Just because the clutch on the front of the compressor spins doesn't mean your compressor is good either, that is the clutch assy spinning not the compressor.
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Old 08-28-2012, 09:14 PM   #12
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Quote:
Originally Posted by Wranglerguy48
Definitely sounds like the clutch. The clutch has to be removed with a puller and can be a major pain.
I have a 99 TJ with the 4.0 and didn't need a puller when I replace my pulley bearing on my compressor. If you have one Bolt centered on your pulley you should be able to use an impact to break the bolt loose. The clutch cover (with any shims) will come off. There is a snap ring clip that needs to come out then the clutch and pulley should slide right off. The electromagnet is behind all of that. I didn't have to replace mine but the FSM will give steps to remove.

I bought a rebuild kit off EBay that included a new bearing, clutch plate and electromagnet for only $55.

Good luck!
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Old 08-29-2012, 01:31 PM   #13
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The low pressure switch will prevent the clutch from engaging until enough pressure activates the switch. When the clutch engages it pushes feon to the high side and disengages again. It will cycle like this in closer increments until the low side reaches 25 - 40 and the high side reaches 200 - 225.

I doubt seriously that he has too much freon because it does not add by itself. If the clutch is not engaging, due to low freon, it would have cycled before the gauge reached yellow. Therefore, without the clutch engaging it would not have pushed freon to the high side to
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Old 08-29-2012, 01:42 PM   #14
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Oops, what I get for typing on iPad. It would not have pushed freon to high side causing overfilling.

The best way to check the clutch is to disconnect the compressor and run a jumper straight from the hot side of the battery to the compressor wire. Do not leave the wire connected or you can burn it up. If the clutch engages, you probably have a bad low pressure switch. You can also use a stethoscope on the NON-turning part of the clutch. Have a friend, while idling the jeep, turn on the ac; please be careful I case it engages. If you hear a clicking noise, you know power is making it to the clutch, from both the high and low switch, and the clutch is bad.

Since the compressor is not pushing freon to the high side, I'm not sure it would be the high pressure switch, but it's not totally out.

If the one gentleman had a compressor that did not require a puller for the clutch, you are fortunate. Every clutch I've changed has required a ac clutch puller; which would be a good reason why they are rented at various part places, and/or sold at many retailers. If your clutch is bad, try the method described by the gentleman who did not need the puller; but if it does not come off, you are like the manny who require a puller. Buy something safe from autozone (like oil) and rent one from them.
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Old 08-29-2012, 05:09 PM   #15
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Quote:
Originally Posted by Wranglerguy48
If the one gentleman had a compressor that did not require a puller for the clutch, you are fortunate. Every clutch I've changed has required a ac clutch puller; which would be a good reason why they are rented at various part places, and/or sold at many retailers. If your clutch is bad, try the method described by the gentleman who did not need the puller; but if it does not come off, you are like the manny who require a puller. Buy something safe from autozone (like oil) and rent one from them.
Here is a video on you tube for the type of ac compressors Chrysler and Jeep use in a lot of their vehicles.



If you're as lucky as I was in having this type a puller is not usually needed. I know every job is different and you never know what you have until you're in to it. Couldn't hurt to follow Wranglerguy48's advice and have one just in case...

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