52 • Controller Operation
CONTROLLER OPERATION
Condensing Unit Pressure Switch Settings
FIXED PRESSURE CONTROLS
Note: Used for Crystal
™
Cooler and Highlight
™
Cooler
Low pressure cut-in/out: 35/15 psig
High pressure cut-out: 440 psig
ELECTRONIC UNIT CONTROL (EUC)
Note: Used for Crystal
™
Freezer, Highlight
™
Freezer, and Reveal
™
Cooler
Low pressure control: Suction pressure transducer (on process port of compressor; has a Schrader valve)
Low pressure cut-in: 30 psig (R-404A) or 22 psig (R-448A)
Low pressure cut-out: 10 psig (R-404A) or 5 psig (R-448A)
High pressure UL safety control: Encapsulated (xed mechanical switch; no manual reset)
High pressure cut-out: 440 psig
Time delay: Built-in (2 second delay on startup; 6 second anti-short cycling delay)
Manual restart or dead band reset: Built-in (hold restart button for 3 seconds when suction pressure is between cut-in and cut-out valves)
Electronic service menu: Compressor starts and runtime for compressor
Alarms:
dLL - High discharge temp alarm
HP - High pressure trip alarm (automatic reset)
HPL - High pressure trip lock-out trip alarm (locks after “HP” alarm happens 4 times in 1 hour; manual reset)
P1 - Suction probe failure (goes into failsafe mode - 5 minutes on, then 5 minutes off)
Pon - Keypad unlocked
PoF - Keypad locked
EE - Module failure
Additional information about EUC:
When the EUC is powered, the compressor light will be on (pressure above 10 psig), unless you are in a dead band. Look at the Carel
case controller to identify if the case is calling to have the compressor running.
The EUC is a compressor low pressure safety. The compressor will stop when the pressure is below 10 psig, regardless of what the
case control signal is. After a safety trip, the compressor will restart when the pressure rises above 30 psig and the case control is
calling for cooling.
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