Installation manual

031-171-C0-003 Rev. C 29
Fig. 3-3, Air Conditioner Control Board
3.0 Installation, cont.
3.3.2 Air Conditioner Control Board
The air conditioner control board (see below) has multiple functions for compressor, condenser fan and
alarm control. It has remote temperature sensors that monitor compressor discharge and evaporator
suction line temperature. It has a board-mounted temperature sensor to monitor the enclosure
temperature, or optional remote temperature sensor to monitor a specific area in the enclosure. The
board incorporates and L.V. shutdown, fixed at 42V for the 48VDC Air Conditioner, and 21V for the
24VDC Air Conditioner.
The temperature sensor on the discharge line of the compressor helps control the condenser fans. At
low outdoor ambient temperatures the condenser fans will cycle on/off to maintain pressure across the
expansion valve.
The temperature sensor on the suction line leaving the evaporator monitors low evaporator temperature.
This can result from blocked evaporator air flow or bad evaporator fans. This condition will send out a
minor alarm and shut down the compressor until the suction lines heat back up.
704-713-
Temperature
Set Point Jumper
Local-Remote Temp
Sensor Jumper
Enclosure Over
Temp Jumper
Minor Alarm LED and
N/C - N/O Jumper
Major Alarm LED and
N/C - N/O Jumper
Under Temp
Shutdown Jumper
DC Power
Input
DC Aux
Output
Major/Minor
Alarm Output
Remote
Enclosure
Temp Probe
+
-
+-