6
System 350
A350E Electronic Cooling Control Product/Technical Bulletin
A
djustments
Follow this procedure to set up the A350E for the
desired operation.
1. Remove the A350E’s cover by loosening the
four captive cover screws.
2. Adjust the differential potentiometer (DIFF) as
desired (the number of degrees between relay
energized and de-energized).
Refer to Figure 7 for a sample multistage
application. If a Celsius temperature reading is
desired, place the included Celsius DIFF label over
the Fahrenheit DIFF label (Punch out the tab in the
center before affixing label to the board.)
OFFSET
ON
OFF
ON
OFF
(+)
(-)
Diffe
re
n
tia
l
ON
OFF
D
iff
er
en
tia
l
ON
OFF
OFFSET
Diffe
re
n
tia
l
ON
D
iff
er
en
tial
OFFSET
OFFSET
A350E
Stage 1
ON = Energized
OFF = De-energized
Diffe
re
n
tia
l
Setpoint
Temperature
S350A
Stage 2
S350A
Stage 3
S350A
Stage 4 S350A
Stage 5
OFF
Figure 7: Typical Multistage Cooling Application
3. Replace the cover, fasten in place with the
four captive screws, and move the setpoint dial to
the desired setpoint.
Note:
The A350E setpoint is factory calibrated at
midscale to a tolerance of ± 1F° (0.6C°). The
setpoint tolerance at the extreme ends of the
setpoint range in relation to the printed scale
plate can be ± 3F° (1.7C°). The D350 Display
Module is unaffected by this tolerance shift.
Use the D350 display for the most accurate
setpoint selection.
C
heckout Procedure
Follow this procedure to verify the A350E control is
connected and functioning properly.
1. Make sure installation and wiring connections are
according to job specifications before applying
power. (Refer to Figure 7 for a sample multistage
application if needed.)
2. Make the necessary adjustments and electrical
connections.
3. Put the system in operation and observe at least
three complete operating cycles before leaving the
installation.
T
roubleshooting
If the control system does not function properly, use
the following procedures to determine the cause of the
problem:
1. Check for proper voltage applied to the A350E.
a. Connect a Digital Voltmeter (DVM) between
the 24V (+) and COM (-) terminals located on
the control’s left side terminal block (Figure 2).
•
If an external transformer is used
, select AC
volts on the DVM and verify that the voltage is
between 20 and 30 VAC.
•
If a Y350R Power Module is used,
select DC
volts on the DVM and verify that the voltage is
between 16 and 38 VDC.
b. If the DVM reading is within the indicated
voltage range, proceed to Step 2.
c. If the DVM reading is
not
within the indicated
voltage range, correct the wiring, replace the
Y350R, or replace the external transformer.
2. Check sensor for proper resistance at a given
temperature. (The resistance across the sensor
changes with the temperature of the sensor.)
a. Disconnect power from the A350E control.
b. Disconnect the sensor from the control and
measure the resistance across sensor leads.
c. When measuring the sensor’s resistance, use
an accurate thermometer to measure the
temperature at the sensor.
d. Refer to Figure 8 to determine the optimal
resistance for the measured temperature.
e. If the measured resistance varies substantially
from the optimal resistance for that temperature,
the sensor or wiring must be replaced.
