hi,
first of all, what do u wanna set? chiller thermostat reading or degree differential? if u r asking about degree differential, i m sorry to tell u that atman chiller can't set a degree differential. this is to say that the chiller's compressor will cut in everytime it senses a 1 degree differential from its thermostat reading. once it has brought the temp in ur tank down to ur set thermostat reading, it will cut out.
as to how to set the thermostat,
1. press set
2. increase or decrease temp showed on the LED accordingly till ur desired temp by pressing the arrow keys.
3. press set again.
note: 1. temp increment/decrement is in unit of 0.5 degrees celsius.
2. temp reading on ur chiller LED is different from ur digital thermometer in ur main tank. due to heat loss, poor sensitivity, etc.
u can contact me to clarify ur doubts again...... anytime.
hope this helps!