The most common cause is a closed valve in the circuit or a clogged filter that restricts water flow. If someone accidentally left an isolation valve shut, or the strainer is dirty, the flow switch will trip.
Pump 1 might not be operational – it could be off due to an electrical issue (blown fuse, overload trip) or mechanical failure, so it's not pushing water.
Less commonly, the flow switch sensor itself could be malfunctioning or stuck, falsely reporting no flow even if water is moving.
Verify that all valves on Pump 1's loop are fully open. Check the supply and return lines for any closed hand valves or automatic valves that should be open during operation.
A blocked filter will reduce flow. If accessible, inspect the chiller's water strainer or filter for debris. Clean out any sludge or blockages to restore proper flow.
Listen or check if Pump 1 is running. If it's not running at all, its breaker or overload might have tripped. You may need to reset the pump's overload (follow steps similar to AL008 if applicable) or replace a blown fuse. Only do this if qualified to work on the electrical panel.
Once corrective steps are taken (valves open, filter clear, pump running), reset the AL012 alarm on the control panel. Hold the alarm reset button for about 5 seconds and release it to clear the error.
After reset, monitor the flow indicator or check piping to confirm that water is circulating properly. The alarm should not reappear if flow is restored. Also, ensure the pump has stable current draw (no further overloads).
There may be a more complex issue such as airlock in the system or a failed pump impeller. A technician can perform deeper diagnosis, check pump performance, and test the flow switch integrity.
