Common Chiller Problems & Error Codes

Most modern chillers are designed with extensive control systems that shut down the machine and display error codes at the first sign of a problem. Understanding these codes helps facilities managers perform first-level troubleshooting.

Important: When a fault occurs, the chiller will stop and an alarm code will appear on the control panel. Often, multiple alarm codes can be recorded for a single event, so it's important to note all active alarms since a chiller stoppage may be caused by more than one issue.

Common Chiller Alarm Codes Overview

Below is an overview of common chiller alarm codes (as seen on a Refcool V15 chiller and similar models) along with a brief description of each issue. Click on each code for detailed guidance including symptoms, likely causes, recommended actions, and advice on when to call a technician.

AL008

User Pump Overload

Indicates the chiller's user pump has tripped on an electrical overload (the pump's fuse/overload protection activated). This usually happens when the pump motor draws too high a current (e.g. a seized or overworked pump), causing the chiller to shut off the pump for safety.

AL012

User Pump 1 No Flow (Flow Switch)

Triggered when no water flow is detected in Chilled Water Circuit #1. The flow switch has not sensed flow – often due to a closed valve or a clogged filter restricting the water, or a failed pump.

AL022

High Chilled Water Temperature

The chilled water returning from the process is too hot beyond the allowable limit. This alarm typically indicates the chiller couldn't maintain the set temperature – often because another fault has reduced cooling capacity.

AL165

Circuit 1 Freeze Protection (Evaporating Temp Alarm)

The evaporator temperature in Circuit 1 dropped too low, risking a freeze-up of the evaporator water. The chiller sensed the water/glycol might freeze and shut down to prevent freezing.

AL171

Circuit 1 High Pressure (HP) Alarm

The refrigerant high-pressure switch tripped on Circuit 1. This means the refrigerant pressure exceeded safe limits – usually due to inadequate heat rejection at the condenser.

AL174

Circuit 1 Low Pressure (LP) Alarm

The refrigerant low-pressure switch tripped on Circuit 1. It detected abnormally low pressure in the refrigerant circuit, often after start-up if pressure doesn't rise enough.

AL175

Circuit 1 Compressor Overload

The compressor's overload protector tripped for Circuit 1. The compressor motor drew excessive current and its safety overload activated, shutting the compressor down.

AL364

Tank Water Level Switch Activated

The chiller's tank water level is low, triggering the level switch alarm. The internal tank level has dropped below the safe minimum – possibly due to a coolant leak or evaporation.

AL366

Fan 1 Overload

Condenser Fan 1's motor overload tripped, meaning the first condenser fan drew too much current and was shut off. This can be caused by a seized fan, debris, or a failing fan motor.

AL368

CpCOe Offline

The chiller's expansion control board (CpCOe) lost communication or is not detected. A critical control expansion board is "offline" which can be due to a loose cable or board fault.

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