Coreco CHt

What does Coreco CHt mean?

The controller signals dirty-condenser trouble in two stages: a pre-alarm (displayed cht) when condenser temperature sits between Ac-AE and the Ac set point, and the full alarm (CHt) once Ac is exceeded. On the Coreco controller (Carel easy / easy compact), CHt is the dirty-condenser alarm, active when probe 3 is the condenser probe (parameter A4=10). It indicates the condenser temperature has exceeded set point Ac for longer than delay Acd. The instrument stops all functions, the buzzer sounds, and

Symptoms

• Display shows CHt flashing, alternating with cht and the temperature
• Buzzer sounds when the alarm is active
• The instrument stops all functions (refrigeration off)
• Condenser running hot, often after a dirty/blocked condenser
• Alarm does not clear automatically — it requires manual reset

Common causes

• Condenser temperature exceeded set point Ac after delay Acd
• Heavily dirty or blocked condenser preventing heat rejection
• Severely restricted condenser airflow
• Failed or weak condenser fan
• Sustained high ambient temperature around the unit

Diagnostic steps

1. 01

   Recognise the shutdown

   CHt is the dirty-condenser alarm — the condenser temperature exceeded Ac and the instrument has stopped all functions. It can only be reset manually.

2. 02

   Mute the buzzer

   Press SET to silence the buzzer; the alarm itself still requires a manual reset once the condenser has cooled.

3. 03

   Clean and clear the condenser

   Clean the condenser coil and remove any dirt or obstruction restricting airflow, since CHt indicates the condenser temperature has exceeded its limit.

4. 04

   Reset the alarm manually

   Reset CHt manually, or by switching the controller off (press UP for 3 s) or powering down; on power-up, if the temperature is still above Ac the alarm will trip again.

5. 05

   Verify parameters and recovery

   Check parameters A4, Ac, AE and Acd, then confirm the condenser temperature stays below Ac after the reset so the unit resumes operation.

When to call a professional

CHt shuts the unit down and needs the condenser overheating resolved before reset. If cleaning the condenser and improving airflow does not keep the temperature below Ac, have a qualified refrigeration technician check the condenser fan and refrigeration system. This work involves the cabinet's electrical and refrigeration circuits reserved for qualified personnel.