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Coreco Ad2

Carel RTN400 controller — End-defrost-by-timeout alarm

Source: Coreco_rtn400_instruction_sheet_9is24288-1_rel0413_en_termostatos.pdf

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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

Diagnostic steps

  1. 01

    Check defrost parameters and efficiency

    Ad2 indicates the defrost timed out. Verify the end-defrost temperature/duration and inspect for ice build-up.

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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

E0

Control probe (probe 1) error — signal interrupted, short-circuited or incompatible probe

E1

Evaporator / defrost probe (probe 2) error — signal interrupted, short-circuited or incompatible probe

E2

Condenser / product probe (probe 3) error — signal interrupted, short-circuited or incompatible probe

IA

Immediate or delayed alarm from the multifunction digital input (external alarm)

dOr

Open-door alarm from the door-switch digital input

LO

Low-temperature alarm — measured temperature below set point by more than parameter AL

HI

High-temperature alarm — measured temperature above set point by more than parameter AH

EE

Unit parameter reading (data) error — saved configuration data error

EF

Operating parameter reading (data) error — manual reset

Ed

Defrost ended by timeout — last defrost stopped on maximum duration, not on temperature

dF

Defrost running — status message shown during a defrost cycle (not an alarm)

CHt

Dirty-condenser warning/alarm — pre-alarm (cht) between Ac-AE and Ac, then alarm (CHt) when Ac is exceeded and refrigeration stops (manual reset)

View all Coreco error codes →