Restricting user adjustment - PENN Controls - A421ABD - A421AED - Electronic Temperature Control - A421 Off‐Cycle Defrost Model

A421 Series Electronic Temperature Controls with Off-Cycle Defrost Installation Guide

Product name
A421 Off‐Cycle Defrost Model
Document type
Installation Guide
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Revision date

You can restrict user adjustment of the A421 Control to the OFF value control band adjustment within a defined range (Figure 1) or no user adjustment at all.

To set the A421 Control to the restricted adjustment mode, position the P1 jumper located on the circuit board next to the TB3 terminal block. See Setting the control to Restricted Adjustment mode.

Note: Setting the A421 Control up in the Restricted mode prevents casual users from over-adjusting the control in your application, or from inadvertently changing the mode of operation from cooling to heating or heating to cooling (by over-adjusting the On value or OFF value).

When the A421 Control is set up in the restricted adjustment mode, the following behavior is enforced:

  • The selected HtS and LtS values define the restricted temperature adjustment range..
  • The On and OFF values define the control band differential, and the control band between On and OFF remains fixed and not adjustable.
  • Only the OFF value can be adjusted, the control band remains fixed, and the On value automatically shifts equal to the OFF value adjustment.
  • The OFF value can only be adjusted to values that maintain the entire control band within the restricted temperature adjustment range defined by HtS and LtS. See Figure 1.
  • The basic and advanced menus are not available. Only the Restricted Adjustment mode menu is available and only the OFF value can be adjusted. See Figure 1.
    Figure 1. Adjustment behavior in Restricted Adjustment mode