Coreco AL2 Error Code
Carel RTN400 controller — LOW temperature alarm 2
Source: Coreco_rtn400_instruction_sheet_9is24288-1_rel0413_en_termostatos.pdf
What does Coreco AL2 mean?
On the Coreco controller (Carel RTN400), AL2 is lOW temperature alarm 2: value read by probe 2 below LA2 after time set in tA2; label AL2 recorded in folder ALr; no effect on control.
Symptoms
- Display/record shows AL2 in the ALr alarm folder
- Cabinet colder than intended
- No direct effect on control (alarm is signalled)
Common causes
- Over-cooling
- Alarm threshold/delay set too tight
- Probe reading low
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Diagnostic steps
Confirm the low-temperature condition
AL2 means the probe exceeded its LA threshold after the alarm delay. Note the temperature.
Review thresholds and cooling
Check LA/tA thresholds and whether the unit is over-cooling.
When to call a professional
If the alarm reflects a genuine refrigeration fault, have a qualified refrigeration technician diagnose the sealed system; this work is reserved for qualified personnel.
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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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