Model 325 to control a Stirling cooler

Hi, 

I have a Stirling cooler that I am trying to control using a model 325 temperature controller. The Stirling's control board uses an input signal between 0 and 5 V and is therefore connected to loop 2 with the 25 Ohm load. My temperature sensor is a PT1000. 
I have been able to manually operate the output using the open loop but am now stuck when trying to do closed loop control. Is it possible to use the heater output for cooling? 

Thanks