Page 134 – Bulletin 100-50-9.1
21. NETWORK AND COMMUNICATIONS
21.1 CONNECTIONS AND WIRING
21.1.1 CASE CONTROL TO DISPLAY MODULE
AND VALVE MODULE
Cable type: 2/22AWG twisted pair (shielded Belden 8723 or
equivalent)
Max Cable length: Up to 20 ft.
Communication: RS-485
21.1.2 CASE CONTROL TO CASE CONTROL
Cable Type: CAT5/CAT5E
Max Cable length: Up to 100 m (328 ft.)
Communication: Ethernet
21.1.3 CASE CONTROL TO BAS
Cable Type: 22AWG twisted pair (shielded Belden 8761 or
equivalent)
Max Cable length: Up to 100 ft.
Communication: RS-485
20. TROUBLESHOOTING
As with any refrigeration component troubleshooting,
actual system conditions should be verified with a gauge
set and calibrated temperature sensor (i.e. verify actual
superheat, sub-cooling and refrigerant condition). This
system information is valuable in determining whether it is
component related or system related.
Typically a refrigerated case should be supplied with at
least 5˚F sub-cooling to the expansion device and should
have at least 5˚F superheat leaving the evaporator. The case
must also have the appropriate saturated suction tempera-
ture to meet the specified case temperature. Typically the
saturated suction temperature (as defined by the suction
pressure) should be maintained at 10˚F below the speci-
fied case temperature. In all instances, consult the refriger-
ated display case OEM specification sheet for sub-cooling,
superheat and suction pressure requirements.
For systems or applications that experience light loads, it
is important that the evaporator and refrigerant lines are
sized correctly. This will ensure proper oil return and will
minimize the effects of oil logging in the evaporator. Refer
to the evaporator manufacturer’s installation instructions.
The following chart can be used as a guide for trouble-
shooting:
Problem Check Solution
Display not powering up Voltage at Display Module (Gnd and 24VDC) Ensure wiring is correct and retighten
Display showing dashes
Communications from the Case Controller (D+
and D-)
Ensure wiring is correct and retighten
Display intermittent Wiring between Case Controller and Display Ensure wiring is correct and retighten
Case Controller not powering up
(power LED indicator not lit)
Voltage at Case Controller (Gnd and 24VDC) Replace power supply if not 24VDC
Wiring between power supply and Case
Controller
Ensure wiring is correct and retighten
Valve Module not powering up Voltage at Display Module (Gnd and 24VDC)
EEPR locked at 100% Rack suction pressure
EEPR locked at 0% For controller alarms
EEV locked at 100% Liquid condition feeding the EEV
EEV locked at 0% For controller alarms
Liquid line solenoid not opening
Wiring from controller to valve
Ensure wiring is correct and that the proper voltage is feeding
the valve
Fuse inside of controller
Ensure fuse is not blown; see Service section for replacement
procedure
Evaporator fans not working
Wiring from controller to valve
Ensure wiring is correct and that the proper voltage is feeding
the fans
Fuse inside of controller
Ensure fuse is not blown; see Service section for replacement
procedure
Case lights not working
Wiring from controller to valve
Ensure wiring is correct and that the proper voltage is feeding
the lighting power supply/driver
Fuse inside of controller
Ensure fuse is not blown; see Service section for replacement
procedure
Defrost heaters not working
Wiring from controller to valve
Ensure wiring is correct and that the proper voltage is feeding
the heaters or hot gas solenoid
Fuse inside of controller
Ensure fuse is not blown; see Service section for replacement
procedure
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