The temperature can be calibrated by using the potentiometer on the device. Turn the potentiometer clockwise to "lower" the temperature. Turn the potentiometer counter-clockwise to "raise" the temperature.
The system only updates the temperature every 30 seconds. For a proper reading, wait 60-90 seconds after making an adjustment to the potentiometer.
If you have a meter that reads frequency, the temperature (in frequency) can be read over a DC square wave. Put your meter between the black and yellow wire and measure the frequency.
FREQUENCY = (4 TEMPERATURE) / 30
If the ambient temperature is 75 degrees:
FREQUENCY = (4 75) / 30
FREQUENCY = 300 / 30
FREQUENCY = 10 Hz