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2004 wj no low pressure switch for AC

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Old 06-14-2018, 09:01 PM   #1  
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Default 2004 wj no low pressure switch for AC

So their is no low pressure switch on the accumulator/drier as expected and the FSM makes no mention of it. They only mention a pressure transducer near the condenser and it seems like this would fill the role of the low pressure switch based on their description but I'm not 100%. Does anyone have any insight on this?
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Old 06-15-2018, 09:59 AM   #2  
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The transducer monitors the high side and changes internal resistance according to pressure, PCM provides a 5 volt signal and ground to the transducer allowing it to monitor voltage changes as refrigerant pressure increases or decreases.

The PCM uses the transducer data to control the compressor clutch and the radiator cooling fan.
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Old 06-15-2018, 02:15 PM   #3  
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Yeah, welcome the the world of smart computers and a data bus! I got blown away when I found out the dash gauges get their inputs from the PCM and not directly from the sensors.
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Old 06-15-2018, 02:32 PM   #4  
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I was wondering because my old compressor seemed to engage the clutch even under vacuum so I thought maybe the low pressure switch was bad. Anyhow I put a "new" (junkyard) compressor in and it behaved normally. AC is back up. Ended up putting in a new accumulator , expansion valve and junkyard compressor. Tore everything out, flushed the system, added oil, installed parts, pulled under vacuum and recharged. It was a fun job, not as daunting as most make it out to be but I, suppose I got lucky the condenser or evaporator weren't bad.
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