Coreco nPA Error Code
Carel RTN400 controller — General pressure switch alarm (n < PEn, Auto Reset)
Source: Coreco_rtn400_instruction_sheet_9is24288-1_rel0413_en_termostatos.pdf
What does Coreco nPA mean?
On the Coreco controller (Carel RTN400), nPA is general pressure switch alarm (n < PEn, Auto Reset): activation of pressure switch alarm by general pressure switch; folder nPA recorded in folder ALr; regulation blocked.
Symptoms
- Display/record shows nPA
- Regulation blocked while the alarm is active
- Pressure-switch input tripped
Common causes
- Refrigeration pressure outside limits (high or low)
- Dirty condenser / restricted airflow (high pressure)
- Low refrigerant charge or restriction (low pressure)
- Faulty pressure switch or wiring
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Diagnostic steps
Identify the pressure fault
nPA is a pressure-switch alarm. Determine whether it is high or low pressure and whether reset is automatic or manual.
Investigate the refrigeration cause
Check the condenser/airflow for high-pressure trips or charge/restriction for low-pressure trips.
When to call a professional
Pressure faults involve the sealed refrigeration system and must be diagnosed by a qualified refrigeration technician.
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Other Coreco Error Codes
Control probe (probe 1) error — signal interrupted, short-circuited or incompatible probe
Evaporator / defrost probe (probe 2) error — signal interrupted, short-circuited or incompatible probe
Condenser / product probe (probe 3) error — signal interrupted, short-circuited or incompatible probe
Immediate or delayed alarm from the multifunction digital input (external alarm)
Open-door alarm from the door-switch digital input
Low-temperature alarm — measured temperature below set point by more than parameter AL
High-temperature alarm — measured temperature above set point by more than parameter AH
Unit parameter reading (data) error — saved configuration data error
Operating parameter reading (data) error — manual reset
Defrost ended by timeout — last defrost stopped on maximum duration, not on temperature
Defrost running — status message shown during a defrost cycle (not an alarm)
Dirty-condenser warning/alarm — pre-alarm (cht) between Ac-AE and Ac, then alarm (CHt) when Ac is exceeded and refrigeration stops (manual reset)
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