Product Overview

A421 Series Standard Electronic Temperature Controls with and without Power Cords Product Bulletin
6
Anti-Short Cycle Delay
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).
The delay interval overrides any Load Demand (On)
and does not allow the output relay to start until the
selected delay interval has elapsed (Figure 12).
This feature is typically used for refrigeration
applications to allow the system pressure to equalize
before restarting the compressor.
Adjustable Sensor Offset
The Sensor Temperature Offset feature allows you to
offset the temperature displayed on the LCD from the
temperature sensed at the A99 sensor. This feature is
useful when the displayed temperature is different from
the temperature measured at the sensor.
Restricted Adjustment Mode
The Restricted Adjustment Mode allows you to limit the
temperature range over which end users can adjust the
control and avoid over-adjustment of your heating or
cooling application.
The adjustment range is limited by setting the high and
low temperature stop values. See Figure 13.
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.
Sensor Failure Mode
The Sensor Failure Mode establishes how the A421
control operates the equipment in the event of a sensor
or sensor-wiring failure. The A421 control may be set to
run the equipment continuously or to shut it down if the
sensor or sensor wire fails. When a failure is detected,
the LCD flashes SF alternately with OP if the sensor
circuit is open, or SF and SH if the sensor circuit is
shorted.
Repairs and Replacement
Do not attempt to repair or recalibrate the
A421 Series Electronic Temperature Control. In case of
a defective or improperly functioning control, contact
your nearest Authorized Johnson Controls/PENN®
Distributor or Sales Representative.
When contacting your Johnson Controls/PENN
distributor, have the model number of the control
available. This number can be found on the label inside
the cover of the control.
Ordering Information
Table 3 provides ordering information for the A421
Standard and Standard Corded models available
through most Johnson Controls/PENN authorized
distributors. See Table 4 and Table 5 to order sensors,
mounting hardware, and other accessories used to
install A421 controls.
Contact your nearest Johnson Controls/PENN
Distributor or Sales Representative to order these
products.
Contact your local Johnson Controls/PENN
representative for more information on options
available for high-volume purchase models with
specific application requirements.
Figure 12: Anti-Short Cycle Delay
Figure 13: Restricted User Adjustment