Johnson Controls A419 Series - Manual (Page 4)

4 A419 Series Electronic Temperature Controls with Display and NEMA 1 or NEMA 4X Watertight Enclosures
Product/Technical Bulletin
For example, if the anti-short cycle delay is set for
7 minutes, the A419 control will not restart the
equipment for 7 minutes after the equipment has cut
out, even if the cut-in temperature value is reached
during the delay. If the temperature reaches the cut-in
value during the delay period, the display flashes
between the sensed temperature and ASd, indicating
that the next On-cycle is being delayed. After the set
delay time has elapsed, the A419 control returns to
normal operation, restarts the equipment (if cut-in has
been reached), ASd stops flashing, and the LCD
reverts to the normal operating display.
Note: Any interruption in supply power to the
A419 control activates the anti-short cycle delay.
Anti-short
Cycle Delay
Load Demand
Output Status
Time
Off
Off
On
On
Load Demand
Overridden
Figure 6: Anti-short Cycle Delay
Sensor Failure Operation (SF) establishes how the
A419 control operates the equipment in the event of a
sensor or sensor-wiring failure. The A419 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. The control implements a 1-minute
delay before initiating a failure response to allow for
verification of the failure condition and to avoid
nuisance failure indications.
Temperature Units establishes the units of
temperature (F° or C°) displayed on the LCD.
Temperature Offset (OFS) establishes the value of
setpoint-shift (in F° or C°) applied to Setpoint (and
Differential) when a (user-installed) circuit is closed
between the binary input (BIN) and common (COM)
terminals. The offset value may be set from 0 to 50F°
or C°.
The Temperature Offset function is used to reset the
Heating Setpoint to a lower temperature (secondary)
setpoint or reset the Cooling Setpoint to a higher
temperature (secondary) setpoint by the temperature
value set in Temperature Offset.
The BIN and COM terminals may be connected to a
(user-supplied) external switching device, such as a
time clock, that has a set of Single-Pole, Single-Throw
(SPST) contacts. Closing a circuit between the BIN
and COM terminals activates the Temperature Offset.
See Wiring.
This function enables the control to alternate between
two temperature setpoints based on the position of the
binary input switch. The difference between the
primary and secondary setpoints (in F° or C°) is set in
the Temperature Offset function (OFS) using the
touchpad. See Setting Other Functions.
Table 1 shows an example of Temperature Offset.
Table 1: Temperature Offset Example
Mode of
Operation
Setpoint
Temperature
Offset Value
Secondary
Setpoint*
Cooling 70° 8° 78°
Heating 70° 8° 62°
* Setpoint when circuit between binary input terminals
(BIN and COM) is closed
When the circuit is closed between the binary input
(BIN) common (COM) terminals, the offset function is
enabled and the A419 control cycles on the secondary
setpoints. BIN is displayed on the LCD above the °F or
°C symbol when the offset is enabled. See Figure 5.
A419 Control Functions Set by Jumper Position
For instructions on positioning jumpers, see
Positioning the Jumpers in the Adjustments section.
See Figure 12 and Figure 13.
Touchpad Lock: The jumper at P5 establishes
whether the touchpad is locked or unlocked. Locking
the touchpad deters accidental or unauthorized
changes to all of the function parameters.
Heating/Cooling Mode is established by positioning
the jumper on the top two pins of the P4 jumper. See
Figure 13.
Setpoint Mode: Removing or installing the lower
jumper at P4 establishes whether Setpoint is the cut-in
temperature or cutout temperature. See Figure 13.
Cooling/Heating and Setpoint Modes
The A419 control may be in four operating modes:
Cooling/Cut-in, Cooling/Cutout, Heating/Cut-in, and
Heating/Cutout. Position the jumpers located on the
circuit board under the A419 control cover to set the
desired mode of operation. See Positioning the
Jumpers.
In Cooling/Cut-in mode the differential is below
Setpoint. The output relay energizes and the LED
illuminates when the temperature rises to Setpoint.
When the temperature drops to Setpoint minus the
differential value, the relay and LED de-energize.