Section 2 – SR-2 Hardware Description
Control and Display Return Air Sensors
These sensors monitor the temperature of the air
returning to the evaporator coil. The sensors are
located in the return air flow and are connected
directly to the microprocessor connector J3. These
sensors are graded sensors and must be replaced
with graded sensors. The microprocessor must be
calibrated to the respective grade of the installed
sensor in order to operate properly. The Control
Return Air Sensor is marked with one yellow cable
tie and is connected to the microprocessor via the
RTP and RTN wires. The Display Return Air Sensor
is marked with two yellow cable ties and is
connected to the microprocessor via the RTRP and
RTRN wires.
Control and Display Discharge Air
Sensors
These sensors monitor the temperature of the air
leaving the evaporator coil. The sensors are located
in the evaporator discharge air path and are
connected directly to the microprocessor via
connector J3. These sensors are graded sensors
and must be replaced with graded sensors. The
microprocessor must be calibrated to the respective
grade of the installed sensor, in order to operate
properly. The Control Discharge Air Sensor is
marked with one red cable tie and is connected to
the microprocessor via the DTP and DTN wires.
The Display Discharge Air Sensor is marked with
two red cable ties and is connected to the
microprocessor via the DTRP and DTRN wires.
Coil Temperature Sensor
This sensor monitors the temperature of the
evaporator coil. The sensor is located on the
evaporator coil header plate and is connected
directly to the microprocessor via connector J3. This
is an un-graded sensor. It is connected to the
microprocessor via the CTP and CTN wires.
Ambient Temperature Sensor
This sensor monitors the ambient air temperature.
The sensor is located in the main unit adjacent to
the condenser coil and is connected directly to the
microprocessor via connector J3. This is an un-
graded sensor. It is connected to the micro-
processor via the ATP and ATN wires.
Spare 1 Temperature Sensor
This optional sensor monitors a temperature as
selected by the customer. This optional sensor must
be installed as required by the customer. This is a
graded sensor. It is connected to the micro-
processor via the STIP and STIN wires.
New Style Graded Sensor
New Style Un-graded Sensor
with Yellow Shrink Tube Marker
2-22
31 January 2005
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