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I am working on a 2011 Murano. The a/c clutch will not engage. The original clutch had burned up and was replaced. It worked for a short time and then quit, and now it won't engage. A/C pressures are good, according to my gauges, and there are no codes in any of the modules (ECM, BCM, HVAC, etc.) There is one issue that I am scratchin my head over though. When you start the engine, no matter what the ambient temp is, or whether the a/c is turned on, both of the radiator cooling fans come on. I can see no unusual data in the ECM, but the a/c pressure sensor reading shows to be at 5.08V. The a/c request PID in the HVAC module show YES when the a/c is turned on, but the ECM shows the a/c request as OFF. Any ideas?
 

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I am working on a 2011 Murano. The a/c clutch will not engage. The original clutch had burned up and was replaced. It worked for a short time and then quit, and now it won't engage. A/C pressures are good, according to my gauges, and there are no codes in any of the modules (ECM, BCM, HVAC, etc.) There is one issue that I am scratchin my head over though. When you start the engine, no matter what the ambient temp is, or whether the a/c is turned on, both of the radiator cooling fans come on. I can see no unusual data in the ECM, but the a/c pressure sensor reading shows to be at 5.08V. The a/c request PID in the HVAC module show YES when the a/c is turned on, but the ECM shows the a/c request as OFF. Any ideas?
The refrigerant pressure sensor reading is abnormal. It should be 1.0 - 4.0 volts assuming the system pressure is normal. The reading you're getting is basically the reference voltage from the ECM so either the sensor is bad or there's a short in that circuit. This is also likely why the cooling fans are running non-stop since the ECM factors in refrigerant pressure when controlling the cooling fans.

You'll find diagnostic procedures in the "Engine Control System" file of the service manual for your car at the nicoclub website: https://www.nicoclub.com/nissan-service-manuals

Let us know what you find.

UPDATE:
Some additional information from the service manual...This graphic succinctly shows the logic behind the cooling fan operation and confirms that when the refrigerant pressure exceeds a certain threshold (as reported by the refrigerant pressure sensor), the ECM commands the fans to operate on high regardless of coolant temperature or vehicle speed.

51793
 

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Thanks for the info "I need coffee"! I replaced the a/c pressure switch, and it fixed the problem. Everything seems to working correctly now. Thanks again for the help!
 

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Thanks for the info "I need coffee"! I replaced the a/c pressure switch, and it fixed the problem. Everything seems to working correctly now. Thanks again for the help!
Your welcome! And, thank you for reporting back that this did fix the problem. Unfortunately, many people come on these forums asking for help and are given advice, but we never hear from them again.
 

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Hey can you share the procedure for changing that and as well where it's located and the part numbers?
 

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Hey can you share the procedure for changing that and as well where it's located and the part numbers?
Sure.
You will have to recover the freon in the system because this switch screws into the top of the condenser.
Remove the black plastic cover over the left (driver side) headlight and left end of the condenser (several push-pin plastic retainers). The switch is on top of the left end of the condenser. It has a three-wire harness connected to it. It uses an o-ring to seal it, so put some refrigerant oil on the new one before installing it. I got the switch at my local O'Reilly Auto Parts store. The part# is 20994.
 

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Are you saying I have to drain the system and recharge it completely? If so I'll probably need to go to a shop who can do that and change it out. I was assuming it just just bolt on given that it's screw on with a wire clipped to it.
 

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Yes. The system must be discharged (drained) and recharged.
I'll keep the part in the car and next season, I'll ask them to discharge the system, i'll pull off grill and swap the pressure switch then get them to recharge the system
 

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Keep in mind that the AC is a designed part of your defroster and windshield clearing system, as it removes moisture from the air. Consider having it fixed now. It's not expensive to have a shop vacuum out the system.
 
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