Coreco Ad2 Error Code
Carel RTN400 controller — End-defrost-by-timeout alarm
Source: Coreco_rtn400_instruction_sheet_9is24288-1_rel0413_en_termostatos.pdf
What does Coreco Ad2 mean?
On the Coreco controller (Carel RTN400), Ad2 is end-defrost-by-timeout alarm: defrost ended due to timeout rather than due to defrost end temperature; label Ad2 recorded in folder ALr, alarm icon permanently on.
Symptoms
- Display/record shows Ad2
- Last defrost ended on time, not on temperature
- Possible incomplete evaporator defrost
Common causes
- Defrost did not reach the end-defrost temperature in time
- Insufficient defrost duration
- Failing defrost heater or defrost-probe issue
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Diagnostic steps
Check defrost parameters and efficiency
Ad2 indicates the defrost timed out. Verify the end-defrost temperature/duration and inspect for ice build-up.
When to call a professional
Repeated defrost timeouts should be investigated by a qualified refrigeration technician (heater/probe).
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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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