Aermec AP2

What does Aermec AP2 mean?

The GR3 controller on NRL, NRA, NRC, NBW and NLW chillers has shut down refrigerant circuit 2 because the high-pressure protection tripped (digital pressure switch or the high-pressure transducer, factory alarm threshold All. AP +39.0 bar). Per the service manual, each alarm stops its own circuit only — the other circuit keeps running.

Symptoms

• Circuit 2 compressor stopped while the other circuit continues
• Alarm shown on the GR3 panel with the alarm relay energized
• Reduced cooling/heating capacity from the unit

Common causes

• Clogged or dirty condensing coil
• External temperature at the unit's operational limits
• First-time heating: system water leaving with high external temperature
• Structural restraints / recirculation (self-boosting) of the condensate air
• On ducted (NRC) versions: additional airflow restrictions in the channelling

Diagnostic steps

1. 01

   Read the alarm on the GR3 panel

   Identify which circuit tripped (AP1/BP1 = circuit 1, AP2/BP2 = circuit 2); the manual notes the alarm history is stored.

2. 02

   Check the condenser side

   Inspect the condensing coil for clogging and verify free airflow — recirculation of condensate air is a listed cause.

3. 03

   Verify operating limits

   Confirm external temperature and water conditions are inside the unit's declared operating envelope.

4. 04

   Check the pressure device

   High-pressure switch is 40 bar rated with manual reset (spare part 9112746); transducer is 0–50 bar (spare 9105093).

5. 05

   Reset and monitor

   After removing the cause, reset the alarm and monitor the circuit pressures through a full cycle.

When to call a professional

Pressure protections on these chillers guard the compressor and the refrigerant circuit. If the alarm returns after clearing the obvious airflow or operating-limit causes, or any work on the refrigerant circuit or the pressure devices is needed, hand off to a licensed refrigeration technician — the service manual directs unresolved anomalies to Aermec's service network.