Refrigeration Controllers

The right refrigeration temperature controller depends on the application, the defrost method and how many loads you need to switch. Start with the operating temperature. Medium-temperature equipment such as display fridges, bottle coolers and chiller coolrooms can usually rely on off-cycle defrost, where the compressor simply stops long enough for the evaporator to clear. A basic single-relay refrigeration controller handles this well. Low-temperature freezers and freezer rooms need an active defrost, either electric heaters or hot gas, so look for a controller with a dedicated defrost output and a second probe on the evaporator to terminate defrost by temperature rather than time alone. Larger systems often add evaporator fan control to stop the fans during defrost and prevent warm air blowing into the cabinet. Finally, check the supply voltage, relay ratings against your compressor load, and the panel cut-out size so the new controller fits the existing opening.

Dixell controllers are widely used in commercial refrigeration, found on everything from supermarket display cases to walk-in coolrooms. The XR series covers most jobs, ranging from simple controllers with off-cycle defrost to models that manage the compressor, defrost and evaporator fans from one compact unit. Many models share a common front panel size, which makes swapping a faulty unit for a like-for-like replacement quick and tidy. Before replacing a Dixell controller, it is worth confirming the fault. A failed NTC probe is a common cause of incorrect readings or alarm codes, and a probe is far cheaper than a new controller. Compare the displayed temperature against a calibrated thermometer, or measure the probe resistance with one of our HVAC test instruments. When fitting a new unit, record the existing parameters first so setpoints, differentials and defrost intervals can be re-entered on the new controller.