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Installer's Guide
SYSTEM SETUP
10. The control board contains a momentary test switch
(S1) and a 4-position installer selectable dip switch
(S2). Both components are located in the lower right
hand corner of the control board. See Figure 8.
TEST SWITCH
The test switch provides a means of verifying that
the fan motor is under the control of the Low Ambient
Controller. A "Y" signal must be present in order to test
the control. Depressing the test switch causes the fan
toalternatelycycleon(for3seconds)andoff(for3
seconds)foratotaltimeof12seconds.Theon/offfan
operation may be observed by watching the fan once
the test function has been invoked or by monitoring the
head pressure using a gauge set. The LED on the solid
state relay should light when voltage is being applied to
the fan motor. Once the 12-second test period is com-
plete the control resumes normal control operation.
DIP SWITCHES
The controller will control to a liquid temperature set
point as determined by the dip switch settings. The dip
switch is used:
1. To select either Automatic Mode or Manual Mode
operation (S2 dip switch 4 setting).
2. To select the liquid temperature set point (S2 dip
switch 1, 2 and 3 settings).
Automatic Mode(S2dipswitch4in"Off"position)
– The controller determines the approach tempera-
ture based upon the liquid and ambient tempera-
ture readings. The approach temperature = liquid
temperature – ambient temperature. The approach
temperature is calculated only when the ambient
temperature is in the range of 65 to 75 deg. F. and
the outdoor fan is on continuously. If the controller
has not yet acquired an approach temperature, S2
dip switch 1, 2 & 3 settings are used for determin-
ing the liquid temperature set point the same as in
Manual Mode. If the controller has acquired an ap-
proach temperature, then the liquid temperature set
point is determined as follows:
Liquid Temperature Set Point =
Approach Temperature + 70 deg. F.
6
Manual Mode (S2 dip switch 4 in "On" position) –
The S2 dip switch 1, 2, 3 settings are read by the
controller and used to determine the liquid tempera-
ture set point when
1.Yisfirstapplied
2. and after initial start-up mode completion, i.e.,
during the system control mode (no sooner than
six minutes after Y is applied). The liquid tem-
perature set point will not change during system
start-up.
The dip switches should be set prior to initial appli-
cation of the Y signal to the controller.
Thedipswitchesshouldbesetforeachspecific
HVAC system based upon the following instructions:
Determine Liquid Temperature Set Point
Reference appropriate high side charging chart for
the unit; liquid pressure for cooling units and head
pressure for heat pump units.
Locate the high side pressure for 70 deg. F. out-
door temperature at the expected indoor wet bulb
temperature. Correct the high side pressure accord-
ingtothespecificindoorunitbeingused.ForHeat
pumps subtract 7 psi, for cooling only units subtract
zeropsi.Usingtherefrigerantpropertieschart,find
the saturation temperature for the calculated liq-
uid pressure. Subtract the anticipated sub-cooling
temperature (typically 12 degrees) from the satura-
tion temperature to obtain an estimate of the liquid
temperature. Set S2 dip switch 1, 2 and 3 settings to
the nearest liquid temperature set point in the table
below.
S2 Dip Switch 4;
Off–AutomaticMode
(recommended setting)
On – Manual Mode
LIQUID TEMP
DIP
SET POINT°F
SWITCH 1
70 °F
OFF
76 °F
OFF
82 °F
OFF
88 °F
OFF
94 °F
ON
100 °F
ON
106 °F
ON
112 °F
ON
DIP
DIP
SWITCH 2
SWITCH 3
OFF
OFF
OFF
ON
ON
OFF
ON
ON
OFF
OFF
OFF
ON
ON
OFF
ON
ON
18-HE46D1-3B-EN
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