With car cold and the key in position 2, press and hold the REST button for >5 seconds until the display changes to a 1 on the left side. Write down the 1 and the number on the right. Press the left auto button to advance to 2 and write those down. Continue until you get back to 1. Also note the ambient temperature at the time of the test.

I'm particularly interested in the reading at #1, which is the inside temperature sensor reading, but the rest may be important if that one is correct. Also reading trouble codes may help, but that's slightly more involved.