The only way to model a refrigeration system properly is to use the Refrigeration objects. The normal zone conditioning equipment (even IdealLoads) does not work well for refrigerated zones.

For refrigerated zones, you will need to use the following equipment:

For the Zone: Refrigeration:AirChiller ZoneHVAC:RefrigerationChillerSet

For the refrigeration system, some combination of the following:

Refrigeration:Condenser:AirCooled

and/or

Refrigeration:Condenser:WaterCooled

and/or

Refrigeration:Condenser:Evaporative Cooled

and

Refrigeration:Compressor

Take a look at the example file: "RefrigeratedWarehouse.idf"