AC decided to quit. No clutch engagement or cooling fan

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03KJSadFace

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While driving on the interstate my AC decided to stop working.

Here's what I've got.
2003 Jeep Liberty Sport
Power to AC clutch fuse. Clutch fuse OK.
No cooling fan or clutch when turning on AC or Defrost.
Cooling fan cycles as it should with engine temp.
Swapped clutch relay. No dice.
Power to 2 of the relay terminals.
Jumpering the low side cycle switch does nothing.
Interior blower motor cycles as it should except nothing on setting 1.
No power to the clutch at the connector mounted to the compressor.

I'm baffled.... any tips or ideas to troubleshoot?

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LibertyTC

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First problem is blower motor resistor pack not working on 1-low speed.
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I'm not sure if that would overall effect system, but needs replacement.
if you in an AC leak situation, low on refrigerant, that would explain why clutch not engaging.
Any engine light on?
 

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Billwill

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Check fuse 15 (10A) in the Junction Block which is the fuse panel inside the cabin.

Check fuse 21 (20A)in the PDC which is the box under the hood.

With Ignition ON if you remove the AC Relay and jumper female pins 30 and 87 inside the empty socket together you should get a "Click" from the AC clutch. Do not run the engine for long in this mode in case the compressor is low on Refrigerant/Oil in which case you will damage the compressor.

This above will tell you if the clutch is OK, if the ground to the clutch is present and fuse 21 is OK and the basic wiring is fine.

The AC Relay should have +12 volts on its pin 86....pin 85 should get switched to ground via a Black/Gray wire from the PCM when AC is switched ON and if the Low Refrigerant Switch is not posting a low level.

So in summary as far as power goes:

Pin 86 and pin 30 on relay should be +12 volts.
Pin 85 should get switched to ground when all is well.
Pin 87 should then pick up +12 volts and energize the clutch...provided the other side of the clutch is at ground permanently.

If you do not have the wiring diagram download the 2003 KJ Service Manual here...includes wiring diagrams section 8W. The relevant page is 8W-42-5.

You may need the diagrams to trace voltage back to the AC ON/OFF switch and to check the Low Refrigerant Switch is happy.

KJ Manuals:Index of /manuals/Jeep/KJ
 

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