8
DDT40 Adaptive Defrost Control
Replacing Existing Defrost Timers
Terminal Identification
The standard DTAV40 terminal identification is identical to the Paragon 8145 with the addition of the “F” terminal. Terminal
identification labels are provided for the other models to be placed over the printed numbers on the printed circuit board.
From Table 1, select the proper label, apply to the printed circuit board and wire per the original wiring or the wiring diagrams
indicated.
“F” Terminal
The DTAV40 contains a normally closed contact between terminals 1 and F. This terminal may be used to switch the fans off
during a defrost rather than terminals 2 and 4. For hot gas defrost applications, with the mode switch set to position “B”, the
fans may be connected to terminal “F”.
8143 Replacement
When replacing a Paragon 8143, wire the termination thermostat to terminal X of the DTAV40 (with the 8143 label attached),
and the adjacent blank terminal. The Paragon timers are wired to terminal X and the blank terminal. If the termination
thermostat is wired to terminal N of the DTAV40 temperature, termination will not occur and may result in burnout of the
DTAV40. See Wiring Diagrams 8 and 9.
8240 Series Replacement
The DTAV40 may be used to replace the Paragon 8240 Series Defrost Timers with integral pressure termination by the
addition of a remote pressure switch wired to terminals Xp and p of the DTAV40 (with an 8240 series terminal label applied).
There must be no external voltage connected to the pressure switch. Set the pressure switch cut-in to the same value as set
on the Paragon defrost timer being replaced. Set cut-out 6 to 14 psi below cut-in. See the wiring diagram
Programming
Setting the Time
Rotate the FM timer dial clockwise until the time of day (AM or PM) of the outer dial is aligned with the triangle marker on the
inner dial.
Note:
The AM and PM locations on the dial represent 6 AM and 6 PM. For example, if the triangle points to the 7 after PM,
then the current time is 7 PM. If the triangle points to the 5 before PM, then the current time is 5 AM.
NOTICE
Do not rotate dial or minute hand counter-clockwise.
Follow this procedure to configure defrost times:
1. On the timer wheel, choose a defrost starting time.
2. Slide the tripper upward that is directly above the
desired time. The timer will initiate a 15 minute defrost
at the configured time.
3. To increase the duration of the defrost, slide up the trippers that are adjacent to the starting time.
Note:
Each tripper on the time wheel represents 15 minutes. For example, to set a 45 minute defrost, slide the two trippers
adjacent to the starting time.
Note:
The AM and PM locations on the wheel represent 6 AM and 6 PM.
4. Repeat steps 1 through 3 as necessary to configure multiple defrost times for a given day.
Defrost Duration:
The defrost duration is settable in 15 minute intervals from a minimum of 15 minutes up to several hours. The defrost duration
determines the termination time. In standard configuration, the contacts between terminals 1 and 3 are normally open and
closed during a defrost to energize defrost heaters; the contacts between terminals 2 and 4 are normally closed with S1 in “A”
position and open during a defrost to de-energize refrigeration and fans.
