Overtime you may notice when measuring the solder temperature in the 485 unit , The measured / Actual temperature of the solder may vary from the display / reference temperature on the temperature controller . 
An offset Value can be applied to bring the Actual temperature to a " True " value so the measured temperature will then match the Display / reference temperature .
To add an offset value to your temperature controller on your 485 unit Please refer to the following steps 
 
    - Ensure your unit is powered off then Open the Small Door on the Face of the temperature controller​
                 *** To open the door push down on the locking tab on the right side of the face directly next to the two ^ arrows ***
                  2. Remove the warning sticker from the control mode selector switch . 
                  3. Your control mode selector should have the switch labeled 1 slid up with the remaining switches down , 
                   You should also see the temperature range dial/switch to the right set at a value of 1 . 
                  4. Slide the switch labeled 4 up . 
                  5. Turn on the 485 unit 
                 6. Push mode key B , This is the furthermost left Key on the temperature controller ( labeled with a arrow in an oval shape ) 
                    The display should now show H0
                 7. By pushing the setting keys you can now enter your desired offset value 
                   ( The setting keys are the middle and right keys labeled with two upward pointing arrows or two downward pointing arrows ) 
                  8. Once the desired Offset value has been input into the controller , you can then Move the switch labeled 4 to its original down position . 
 
View attached photos for reference on how to access and change the offset on your 485 . 
for further assistance Please do not hesitate to reach out to American Hakko Products . 
661-294-0090