XJ AC Not working
#1
Junior Member
Thread Starter
XJ AC Not working
Another XJ AC system not working post. Ive poured over forums and cant find a solution.
2000 XJ AC compressor wont turn on. When I turn on the AC, I can hear the engine revs go up. It did this when my AC used to work.
Things Ive done:
Low Pressure switch = Good
High Pressure switch = Good
E Fan works. Turns on when Jeep is hot.
Low side pressure 90psi
High side pressure 90psi
(I believe the same pressures means the system has normalized)
AC Clutch Fuse = Good (This fuse has caused my system to stop working in the past. 20 years of built up corrosion)
Ive jumped the Low Pressure switch. It didn't make the compressor turn on but the RPMs still went up just as if it were plugged in.
Same thing when I jumped the High Pressure switch.
One thing I haven't tried is jumping the compressor clutch. I believe this is done by putting 12v power from the battery to the 1 wire at the back of the compressor. Is this correct?
The AC Relay isn't getting any power. Ive hooked up my multi meter and I cant get a reading. Tried jumping the relay but cant get anything to happen.
Someone on Facebook if I tested the power from the PCM or the power from the battery. Im not sure which terminals those are. I just know I didn't have power.
Thoughts on what might be causing this?
2000 XJ AC compressor wont turn on. When I turn on the AC, I can hear the engine revs go up. It did this when my AC used to work.
Things Ive done:
Low Pressure switch = Good
High Pressure switch = Good
E Fan works. Turns on when Jeep is hot.
Low side pressure 90psi
High side pressure 90psi
(I believe the same pressures means the system has normalized)
AC Clutch Fuse = Good (This fuse has caused my system to stop working in the past. 20 years of built up corrosion)
Ive jumped the Low Pressure switch. It didn't make the compressor turn on but the RPMs still went up just as if it were plugged in.
Same thing when I jumped the High Pressure switch.
One thing I haven't tried is jumping the compressor clutch. I believe this is done by putting 12v power from the battery to the 1 wire at the back of the compressor. Is this correct?
The AC Relay isn't getting any power. Ive hooked up my multi meter and I cant get a reading. Tried jumping the relay but cant get anything to happen.
Someone on Facebook if I tested the power from the PCM or the power from the battery. Im not sure which terminals those are. I just know I didn't have power.
Thoughts on what might be causing this?
#2
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Join Date: Jun 2016
Location: Santa Clarita California
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Year: 2001
Model: Cherokee (XJ)
Engine: 4.0L
Ok , Have you check the compressor clutch plate if it is to far from the clutch pully it can't pull the clutch plate in to turn on the compressor ?
#4
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Join Date: Jun 2016
Location: Santa Clarita California
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Year: 2001
Model: Cherokee (XJ)
Engine: 4.0L
Wow I did miss that . the computer runs the ground side of the relay so if he's not getting power to the relay he needs a wiring diagram to see where the power comes from .
#5
Junior Member
Thread Starter
Still haven’t had a chance to jump the compressor. Hopefully tomorrow. Motley Crue concert tonight 🤘🏻😎🤘🏻
#6
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Join Date: Aug 2020
Location: SoCal
Posts: 1,753
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382 Posts
Year: 1988
Model: Cherokee (XJ)
Engine: 4.0L
So jump the compressor clutch first with the engine off. You should see and hear the plate engage. Next with engine on. Sounds like you have manifold gauges so I would use them to verify pressures once the AC runs for a few minutes.
The clutch relay connects to the PCM on C3 Pin 1. At the relay connector, PCM C3 Pin1 connects to slot B3.
The clutch relay connects to the PCM on C3 Pin 1. At the relay connector, PCM C3 Pin1 connects to slot B3.
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