A/C will not turn on

2000 NISSAN MAXIMA
240,000 MILES • 3.0L • 6 CYL • 2WD • AUTOMATIC
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CISCO4512
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Hey all, so the A/C is just blowing hot air. I was going to recharge it and noticed the clutch not engaging at all. checked all fuses and relay first. all is good could not figure out why but if I take a piece of wire and jump it at the relay it works clutch engages blows cold air. changed out relay but still the same. any ideas?
Sep 4, 2019 at 4:06 PM
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ASEMASTER6371
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Good evening.

I attached a wiring diagram for you to view. With the key on, verify there are 2 powers to the relay.

Roy
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Sep 4, 2019 at 4:20 PM
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CISCO4512
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I checked power i do have power at relay at 5 and 2 and nothing at 1 and 3.
Sep 4, 2019 at 5:04 PM
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ASEMASTER6371
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Okay, the ECM is what grounds the control side of the relay to engage the compressor.

There is a pressure switch on the little line for the Freon. It has 3 wires. Test for 5 volts to the red wire with the sensor disconnected.

Roy

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Sep 4, 2019 at 5:19 PM
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CISCO4512
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Okay, I just check the pressure switch I do have 5 volts at the red wire.
Sep 4, 2019 at 5:47 PM
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ASEMASTER6371
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Okay, is there another 5-volt wire as well?

Roy
Sep 4, 2019 at 5:51 PM
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CISCO4512
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I double checked that just now and nothing on the other two.
Sep 4, 2019 at 5:58 PM
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ASEMASTER6371
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The middle wire is the signal wire and should also have 5 volts. You may have a bad ECM.

Roy
Sep 4, 2019 at 6:10 PM
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CISCO4512
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How do I diagnose the ECM to know for sure? And thanks for all your help, much appreciated.
Sep 4, 2019 at 6:39 PM
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ASEMASTER6371
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The 5 volts comes from the ECM.

In my first response, I attached a wiring diagram. Follow the wire back to the ECM and see if there is power coming out at that pin.

Download the wiring diagram to your laptop and then enlarge it so you can see it better.

Roy
Sep 4, 2019 at 6:53 PM
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CISCO4512
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Thank you.
Sep 4, 2019 at 6:55 PM
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ASEMASTER6371
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You are welcome.

Roy
Sep 4, 2019 at 6:57 PM