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Johnson Controls Penn A421 Series - User Manual

Johnson Controls Penn A421 Series
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LIT-1900935
2020-04-14
A421 Series Electronic
Temperature Controls with Off-
Cycle Defrost Catalog Page
A421ABD, A421AED, A421AED
Description
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/Off status of the output relay.
The A421 Controls are available in 120 VAC and 240 VAC
models.
The A421 Control with Defrost allows you 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 be set to 0 for no defrost interval. You can
also start or stop a defrost off-cycle in two ways: press
the three-button touchpad on the Advanced Menu or
connect a momentary switch to the Binary Input (BIN).
The A421 also provides 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°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 and Type 4X, IP66 watertight, corrosion-
resistant surface mount enclosures.
Refer to the A421 Series Electronic Temperature Controls
Product Bulletin (LIT-12012219) for important product
application information.
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Johnson Controls Penn A421 Series Specifications

General IconGeneral
Power Consumption5 VA max
Relative Humiditynon-condensing
Output TypeRelay
MountingSurface mount
Control ModeOn/Off
Enclosure RatingNEMA 1
Input TypesThermistor
Sensor TypeThermistor

Summary

A421 Series Electronic Temperature Controls Overview

Standard Electronic Controls

Details the A421 Series Standard Electronic Controls with SPDT relay, LCD, touchpad, and LED indicator.

Off-Cycle Defrost Functionality

Explains setting defrost periods, intervals, and manual activation methods for the A421 Control with Defrost.

Advanced Control Features

Covers sensor offset, temperature setback, anti-short cycle delay, and user adjustment modes.

Enclosure and Mounting Options

Details Type 1, IP20 and Type 4X, IP66 enclosures for surface or DIN rail mounting.

A421 Temperature Control Applications and Features

Product Applications

Lists sample temperature control applications for refrigeration and HVAC equipment.

Control Front Panel LCD

Displays temperature, parameters, status, backlight intensity, and custom icons.

Programming Menu Levels

Offers two levels of parameter adjustment and control for setup.

Temperature Adjustment and Setback

Covers On/Off adjustment, switch-activated setback, and anti-short cycle delay.

Sensor Offset and Failure Modes

Details adjustable sensor offset, restricted adjustment mode, and sensor failure behavior.

Backlight and Repair Information

Covers LCD backlight adjustment and guidance for repairs.

Ordering Information

Guides on ordering sensors, hardware, and accessories from distributors.

A421 Series Selection Charts

A421 Standard Electronic Temperature Control Models

Lists A421 models, enclosures, and included sensors with their specifications.

A99 Series Temperature Sensor Specifications

Details various A99 PTC temperature sensors, probe types, cable lengths, and operating ranges.

Accessories for A421 Controls

Lists available accessories like DIN rail sections, clamps, clips, sun shields, and enclosures.

Technical Specifications and Support

A421 Electronic Temperature Control Specifications

Provides detailed specs for power, supply, ambient conditions, temp range, sensor, enclosure, and compliance.

Software Terms of Use

Outlines terms of use for the product's software and hosted services.

Contact and Support Information

Lists regional contact points and provides links for customer support.

Product Warranty Details

States the product is covered by a limited warranty with details available online.

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