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Hello community! I am new here. I hope you can help. I have a 2012 Nissan Murano that the A/C stopped working. So I picked up some refrigerant thinking it was low. When I went to add it, the gauge wouldn’t give me a reading. Then I noticed that the clutch wasn’t engaging. So I tested the low pressure sensor and clutch. The clutch was bad. I took it to my mechanic. He replaced the the clutch and compressor. Also, the relay was bad. So he replace that too. From the electrical panel in the engine compartment to the the compressor, everything tested positive. However, no A/C. His scan tool couldn’t check from the electrical panel back to the controls in the dash. So I ordered a new control panel on Ebay. I installed today. Still no A/C. Any advise? Please help.
 

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There are a bunch of things that need to work right for a Nissan Auto A/C system to turn on the compressor. First, the A/C Auto Amp (HVAC control head) needs to see all three temperature sensors reading normally. Those are Ambient up in the grille, In-Cabin near the driver's right knee, and Intake located on the A/C evap. When any of those fails open-circuit, the temperature reads "Alaska" and the HVAC won't allow the compressor to turn on. If those are okay, the compressor request and fan signals are passed to the BCM. If the fan signal isn't getting there, the BCM will veto the compressor request. The BCM then sends a CANbus signal to the ECM requesting compressor. The ECM will veto the request if it sees low refrigerant pressure. When the RP sensors fail they usually read zero, so a dead sensor will cause an inop compressor. If all these tests are passed, the ECM passes the request via CAN to the IPDM, which actually works the relay.
 
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