You're correct, the temp gauge does affect the AC unit. Here's some info that you'll find helpful.
07wHiTE 3.5SE 6sPD wrote: ↑
Tue Jul 27, 2010 7:22 am
I had the same problem. It also affects the air conditioning compressor from working correctly. Take a look by your front bumper to the right of the OEM license plate mount... you'll see a sensor there with two wires colors blue and brown. That's the outside air temp wires and sensor. There is a spot on the connector where you squeeze and it allows for it to be released. Then you can check the connection point for corrosion or water to see if its creating a short. If it's reading 0 degrees and icy there is a short, if it's reading dashes, --- degrees the circuit is open. The sensor works like a thermonuclear in which the higher the temp the lower the resistance. If anyone has access to a multi-meter set it to the k-ohm range disconnect the two wire connector going into the sensor on the bumper and test the resistance output from the sensor. At around 85 degrees you should get around 1.2 k-ohm but if you get an open reading or a reading indicating a short then you need to replace that sensor which is around 30 dollars from the Nissan dealer. if the sensor is good, trace those two wires (blue and brown) back into the IPDM which is a black box resembling a vehicle's ECU (located right in front the battery on a steel bracket). In my case the brown wire had a cut creating an intermittent connection. Any questions feel free to ask and i can try to be more clear. Good luck.
If the Ambient Temperature Sensor is defective then you can replace it yourself. The part isn't that expensive, but the correct one depends on when your car was built.
Production Date: 10/2013-12/2015
Part Number: 27722-3RA0A
Production Date: 12/2015-09/2016
Part Number: 27722-3VA0A