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Discussion Starter · #1 ·
Some seriously confusing issues going on with my 2017 Pathfinder. 130k miles.

About a year ago I found the wire to the ambient temp sensor partially broken after my wife was having erratic A/C, sometimes it would blow cold and other times it would be close to the outside air temps. At the same time the temp gauge was saying -22 F. The problem seemingly went after I fixed the wiring and replaced the sensor.

Fast forward a few months and the ambient temp is all over the place, some days its accurate, some days it says -22F, -18F, and commonly with start at -6F or so and slowly (over the course of an hour or two) come up to the actual temps.

To make this more complicated, the AC will function perfectly fine while the temp is at -22F. Other times, when the temp is jumping around the AC will blow full cold, then ambient air, then cold again. On occasion, I have to shut off the car and turn it back on to get cold air again. The blower always continues to blow, its not stopping or changing at all.

My wife is ready to burn the car to the ground as it gets miserable pretty quick in Florida right now.

Advice? Help?
 

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I'd revisit the repair. -temps is a classic sign of a broken sensor, wire, or high resistance in that wire. Since the sensor is slow to respond to changes, it could explain why it is acting erratically. That sensor is directly involved in the AC operation.

Recheck your repair. If you used some crimp connectors, they are notorious for being a bad fix. Solder and weatherproof shrink wrap is my personal go to.
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Discussion Starter · #4 ·
Anyone have a schematic diagram I could use to find a way to check for a short or break in the line?


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2019 Nissan Pathfinder SV 4x4
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Is your ambient temperature still reading all over the place? If it's not and the indication is accurate, I'd focus somewhere else.

I just watched a South Main Auto channel episode the other night with a 2014 Nissan Altima. The pressure switch on the condenser coil had a wire corroded right off the connector. Some of the wires associated with the a/c system are very thin and fragile on Nissans. It's probably not your issue, but something to consider.

There is a link somewhere on this site for factory service manuals up to the 2016 model year.
 

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Id be surprised if it wasn't right at the sensor where it was before. How exactly did you repair the wire before?

This is where having the right scantool makes this so much easier. Is the compressor still running when it is blowing warm air?
 

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Discussion Starter · #9 ·
I tested the connection. I can’t find any issues, the positive is giving me 5V, ground side is solid, can’t get either to give me a bad indication. Sensor was giving the correct ohms in 90 and 70 degree weather. According to the troubleshooting guide it points at the A/C auto amp. Not positive on what that is or how to test it yet. Still trying to figure it out.


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Discussion Starter · #10 ·
As I try to figure this out my wife reminded me that we have an intermittent issue with the rear A/C just randomly shutting off. Based on that, would the AC auto amplifier be a good target? Cheapest I can find is $142. I don't want to just throw money at it but I feel like that is a logical common element from what I have seen. Thoughts?
 

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Possibly, but it sounds like you took those voltage measurements with the sensor unplugged. It's really important to take them with the car on or running and plugged in. The circuit isn't loaded at all when it's unplugged. The 5v is good and means that the wire is good all the way to the ecm, but we don't know about the ground wire yet. The sensor must at least be intact internally to have provide a reading, but ohm tests are only really accurate when it is out of spec. Good ohm specs can still be a bad sensor. If that all checks out,

You really need a scantool to accurately diagnose these. The AC auto amp could be bad, but it also is the part that processes the data from all of the sensors and other control units, so if it's getting bad data, it's just going to respond to it. Id really want to see all of the data inputs while it's acting up to see who is at fault.

The last thing is that before ever replacing a module, you always want to do those loaded circuit tests on all of it's powers and grounds.
 

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Maybe I am missing the point here and sorry to keep beating a dead horse...

If we're still talking about the ambient temp sensor, if the temperature is indicating spot on in the vehcile, how could there be a problem with it?
 
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