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USER GUIDE
Figure 20: Activating Relay #2
DISPLAY – TOUCH SCREEN VERSION
Figure 21: USB Port
The RS485 port on the relay board is used to connect the
keyboard (see Figure 22).
RS485
Connection on Relay Board
Figure 22: RS485 Port Connection
Touch Screen Display Troubleshooting
Monitor the communication between the Display and Power
Boards by looking at signals Ext/Int on the bottom left side
of the Display. Both signals blink "Blue" if communication
Troubleshooting
USB Port
Front Side
RS485
Back Side
Connection on Display
is good. One or both will blink "Red" if an error is occurs
(see Figure 23). Check the connection cable for continuity
to find a cable issue, or troubleshoot the Display or Power
Boards.
Figure 23: Ext/Int Indicators
REFRIGERANT PRESSURES CHECKS
High or Low refrigerant pressure levels are dependent on:
•
Ambient temperature
•
Heat load in the cabinet (Full or Empty)
•
Status of the cycle (hot food, frozen food, etc.)
•
Cabinet temperature
•
TX valve regulation
•
Evaporator coil air flow
•
Condenser coil air flow
Checking High and Low pressures on the unit cannot
determine if the unit is operating correctly. Careful
analysis, based on the conditions listed, is necessary to
properly diagnose a problem.
For example: Checking the suction pressure results in a
reading of 0.1 barg. This pressure could be correct if the
cabinet temperature is at the minimum (-40°C) and the
evaporator temperature is at -45°C.
If this is not the case, the evaporator may not be getting
sufficient refrigerant and the actual evaporator temperature
could be much higher than -45°C. It is not recommended
to base any troubleshooting conclusions solely on the
pressure readings.
SUCTION PRESSURE: 0.1/0.2 barg
Measure this pressure when the cabinet temperature is at
-40°C with the compressor running.
DISCHARGE PRESSURE: 16 barg
This pressure can vary greatly and reach up to 25 barg
psig, depending on the ambient temperature and heat load
inside the cabinet. Very high discharge pressures can cause
the pressure switch to signal an alarm.
40
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