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ManualsBrandsJohnson Controls ManualsA421 Series Temperature ControlsSingle Stage Digital Temperature Control (120/240v SPDT)

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Refer to the QuickLIT website for the most up-to-date version of this document.

A421 Series Standard Electronic Temperature Controls with and without Power Cords Product Bulletin

Description

The A421 Series 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/Off status of

the output relay.

The A421 controls are available in low voltage 24 VAC

and high voltage 120 or 240 VAC models, which

provide options for most refrigeration and HVAC

applications.

The A421 controls provide heating or cooling control,

sensor offset, temperature setback, adjustable

anti-short cycle delay, and a restricted user adjustment

mode. The temperature units can be displayed in °F or

°C. The temperature adjustment range is -40 to 212°F

or -40 to 100°C.

The A421 controls are available in Type 1/IP20

high-impact plastic enclosures suitable for surface or

DIN rail mounting and Type 4X/IP66 watertight,

corrosion-resistant surface mount enclosures. See

Figure 1 through Figure 3.

Some A421 Series control models are equipped with

factory-installed power cords. The power cords provide

convenient plug-in connection and control of 120 VAC

heating and cooling equipment.

Figure 1: Standard Temperature Control with

NEMA Type 1/IP20 Enclosure

Table 1: Features and Benefits (Part 1 of 2)

Features Benefits

Control Front Panel LCD Displays the temperature, parameters, and status and allows you to adjust

the backlight intensity for ambient light conditions. Custom icons display

the system and control status.

Basic and Advanced Programming Menu Provides two levels of parameter adjustment and control setup, allowing

you to set up advanced features in one menu and easily adjust basic

parameters in the other menu.

On/Off Temperature Adjustment Allows you to select the temperature values at which the relay turns On

and Off, which automatically defines the Heating or Cooling mode of

operation.

Switch-Activated Temperature Setback Allows you to shift the On/Off temperature by an adjustable setback value.

When a user-supplied switch closes the binary input control circuit, the

control operates at the defined setback temperatures.

Adjustable Anti-Short Cycle Delay Allows you to select the minimum time the output relay remains off before

the next on cycle; avoiding short cycling, hard starts, and nuisance

overload outages on compressors and other inductive applications.

A421 Series Standard Electronic Temperature

Controls with and without Power Cords

Product Bulletin

A421ABC-x, A421ABG-x, A421ABJ-x, A421AEC-x,

A421AEJ-x, A421GBF-x, A421GEF-x

Code No. LIT-12011972

Issued November 6, 2015

Summary of content (9 pages)

PAGE 1
A421 Series Standard Electronic Temperature Controls with and without Power Cords Product Bulletin Code No. LIT-12011972 A421ABC-x, A421ABG-x, A421ABJ-x, A421AEC-x, A421AEJ-x, A421GBF-x, A421GEF-x Issued November 6, 2015 Refer to the QuickLIT website for the most up-to-date version of this document. Description The A421 Series controls are single stage, electronic temperature controls with a single-pole, double-throw (SPDT) output relay.
PAGE 2
Table 1: Features and Benefits (Part 2 of 2) Features Benefits Adjustable Sensor Offset Allows you to adjust the displayed temperature to the actual sensed temperature. Optional Restricted Adjustment Mode Allows you to restrict the On/Off adjustment to your defined temperature range. Sensor Failure Mode Allows you to select the relay On/Off state in the event of a sensor or sensor wire failure. Backlight Brightness Level Allows you to adjust the LCD backlight intensity.
PAGE 3
Space Heating Transportation X X X X X X X Power Cord X X X X X X X A421ABJ Power Cord2 X X X X X X X X A421AEC Standard X X X X X X X X X X X X X X X X X X X Power Cord A421GBF Standard X X X X X X X X X X X X X X X A421GEF Standard X X X X X X X X X X X X X X X 1. 2.
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Figure 6: A421ABG Control with Two Power Cords, Dimensions, in. (mm) Figure 8: A421ABJ Control A99 Sensor and Bracket with Power Cord, Dimensions, in. (mm) Type 4X/IP66 Watertight, Corrosion-Resistant Enclosures Figure 7: A421AEx and A421GEx Controls, Dimensions, in.
PAGE 5
A421 Control User Interface SPDT Relay Output The terminals on the TB2 terminal block are connected to an SPDT dry-contact relay in the A421 control. The A421 Electronic Temperature Control can be wired to use the same power source to power the control and power the controlled load. The control can also be wired to control the relay based on the On/OFF temperature values.
PAGE 6
Anti-Short Cycle Delay You can also set the restricted adjustment range equal to the On and Off temperatures to eliminate any temperature adjustment on the control by end users, effectively locking the control adjustment features. The Anti-Short Cycle Delay feature allows you to select the minimum time the output relay remains Off de-energized) before the next on cycle can start (energize).
PAGE 7
Table 3: Standard A421 Electronic Temperature Control Selection Chart Product Code Description A421ABC-02C Line-Voltage Type 1 Electronic Temperature Control: Type 1 (NEMA), IP20 standard enclosure for DIN rail and surface-mount applications. Rated for 120/240 VAC. Includes an A99BB-200C temperature sensor with 6.6 ft (2.0 m) cable. A421ABC-03C Line-Voltage Type 1 Electronic Temperature Control: Type 1 (NEMA), IP20 standard enclosure for DIN rail and surface-mount applications. Rated for 120/240 VAC.
PAGE 8
Technical Specifications Table 4: A99 Temperature Sensors Selection Chart1 Product Code Description A99BA-200C PTC Temperature Sensor: Standard probe 2 in. (5.1 cm) with 6.6 ft (2.0 m) shielded PVC cable; Ambient operating temperature range: -40 to 212ºF (-40 to 100ºC) A99BB-25C PTC Temperature Sensor: Standard probe 2 in. (5.1 cm) with 9-7/8 in. (0.25 m) PVC cable; Ambient operating temperature range: -40 to 212ºF (-40 to 100ºC) A99BB-200C PTC Temperature Sensor: Standard probe 2 in. (5.
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Table 6: A421 Series Electronic Temperature Controls Power Consumption 1.