The LA2 alarm on a pharmacy refrigerator with a Dixell controller is a freeze prevention alarm that often indicates a lack of airflow from the bottom of a fridge to the top.
What is it for, and what happens when it goes off? The sensor that triggers the LA2 alarm is situated after the evaporator as the air enters the workspace. In the event of reduced airflow because of a blocked shelf, the control sensor at the top of the fridge will be warmer and will call on the refrigeration to work harder; therefore, the bottom of the refrigerator can receive much cooler air. The LA2 sensor, when in alarm state, will stop the compressor and prevent the bottom shelf temperature from going under 2°C.What causes the LA2 alarm? The primary reason that the LA2 alarm will activate is because of excess stock being placed on a shelf. Thermoline recommends 50mm from the side walls and back panel, with spacing between the stock on the shelf. Lack of space or "crowding" is also mentioned in section 5.5, storage of the national vaccine storage guidelines.
What to do? Generally, a redistribution of the stock to prevent crowding will alleviate the problem.
Other causes? The LA2 alarm can also activate after prolonged or frequent door openings as the refrigeration is called upon to bring the fridge back to optimal conditions. Warm stock being placed in the refrigerator may also cause the LA2 alarm to trigger as the refrigeration system tries to compensate for the increase in temperature. In these events, the fridge should be able to correct itself eventually.
If it continues? If you have tried moving stock with a stable fridge and the LA2 alarm continues activating, please get in touch with Thermoline's service team at service@thermoline.com.au .
How else can I protect my vaccines? In the unlikely event of a controller malfunction that may cause the refrigeration relay to weld shut (i.e. the compressor stays 'on'), the fridge will continue to cool regardless of any alarms. Thermoline can add an optional LTPC (low temperature protection cutout) which is a mechanical thermostat that will override the controller and turn the compressor off. It will prevent your vaccines from freezing and allows the compressor to restart only after the fridge temperature warms, keeping the stock at the correct temperature until the malfunction can be repaired or the stock moved.