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Another AC Clutch Issue

The Badness

NAXJA Forum User
Location
Fl
Hey guys, got a good one for you. 2001 Xj sport 4.0 4wd aw4.

Issue is the AC. I start her up, turn on the ac and for about 20-30 minutes, the compressor clutch stays engaged and the air is nice and cold. After that time frame the clutch disengages and reengages a couple times with a 5-10 second interval. Then i can hear the engine rev up a bit, as if it were to reengage the ac clutch...but this time, no engagement and the warm air starts to blow. So i get my handy paper clips out, and pull the plug to both the low pressure cut off and high pressure cut off, and jump them both for just long enough to confirm clutch engagement....again the engine revs up and i can feel the a/c clutch relay click, yet no clutch engagement. I whip out the tester, and there is no power to the ac clutch wire despite the ac clutch relay being engaged. Swapped relay...no change. swapped high and low cutoff with a working pair...no change. then to confirm clutch operation, i put 12v to the clutch wire and she engages...so the clutch is fine, the cut offs are fine, the relay is fine..is the a sensor elsewhere that determines power to clutch? Oh and shut her off and let her sit for a bit, and the AC goes back to normal for another 20-30 minutes. Stumped at this point :wierd:
 
Once the A/C clutch relay is energized, the clutch should receive power, the high and low pressure switches report to the ECM and have no connection to the A/C clutch relay.
Confirm the A/C clutch relay output is hot, when energized, then check the wire and connections between the relay and A/C clutch.

If you have a FSM, the wiring schematics show how the relay and pressure switches are wired.
 
I've never seen a complete wiring diagram for a 2000, but I think the PCM is more connected than you might think. One thing you definitely want to try is under the "defrost" mode.
 
Actually, i shot myself in the foot during the testing phase and somehow blew the 20 amp fuse for the clutch with my tester....thats where i had no power to the clutch despite all of that. So i put the new fuse in and discovered the clutch trying to engage but getting stuck...probably needs a shim removed. Thank you all for the help. actually i did find a complete diagram for a 2001....the PCM is INCREDIBLY involved in the "decision making" of the ac system
 
The ECM does control everything in the A/C system.
The A/C compressor relay is controlled only by the ECM, nothing else is in the circuit to cut power. The high and low-pressure switches connect directly to the ECM .

From the 2000 FSM
47067819914_5dde6bed77.jpg

33980026208_d110661211.jpg
 
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