The A421 Series Standard Electronic Temperature Controls are single-stage electronic temperature controls with a single-pole, double-throw (SPDT) output relay. The controls feature an adjustable backlit LCD for viewing the temperature and status of other functions, and a three-button touchpad for setup and adjustment. An LED indicates the On or Off status of the output relay. The A421 Controls are available in 120 VAC and 240 VAC models.
You can use the defrost A421 Control to set up regular, passive defrost periods of 1 minute to 99 minutes. The defrost interval can range from 2 hours to 24 hours, or you can set it to 0 for no defrost interval. You can also start or stop a defrost cycle in two ways: use the three-button touchpad on the advanced menu or connect a momentary switch to the binary input (BIN).
The defrost A421 control also provides sensor offset, temperature setback, adjustable anti-short cycle delay, and a restricted user adjustment mode. The control can display the temperature units in °F or °C. The temperature adjustment range is -40°F to 212°F or -40°C to 100°C.
The A421 Controls are available in Type 1/IP20 high-impact plastic enclosures suitable for surface or DIN rail mounting, as shown in the following figure, and Type 4X/IP66 watertight, corrosion-resistant, surface-mount enclosures.
You can rotate the control housing base on the Type 4X/IP66 models 180º relative to the control housing cover and LCD. You can bring the electrical connection to either the top or bottom of the mounted control. Do not twist the wiring harness between the housing base and cover more than 180º.
