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REFRIGERATION

Troubleshooting

Vaccine fridge temperature excursion

Vaccines are typically stored between +2 and +8 °C. A temperature excursion is any time the storage temperature goes outside that range, warmer or colder. Both matter: some vaccines lose potency when warm, and some are damaged by freezing even though they look normal afterwards. This page covers equipment and good practice only. Whether a vaccine can still be used after an excursion is not a decision for staff or a refrigeration technician; it is made under your immunisation programme's or regulator's rules, often with the manufacturer's data. Your job in the moment is to protect the stock, record the facts and report.

First, check these

  1. Do not discard the vaccines and do not use them. Mark them clearly as 'do not use' and keep them together.
  2. Move them to another unit that is holding +2 to +8 °C, or to a validated cold box as your procedures describe.
  3. Record the current temperature, the minimum and maximum readings, the time the excursion was found and how long it lasted if your logger shows it.
  4. Report immediately to your supervisor or cold chain officer and follow your programme's excursion procedure.
  5. Check indicators such as vaccine vial monitors if your programme uses them, and record what you see.

Likely causes

  1. 1. Door left open or not sealing

    You can check this

    Signs: Warm excursion during busy sessions or after stock checks; door found ajar; gasket damaged.

    Fix: Close the door and check the seal. Replace damaged gaskets and fit a door alarm if available. Train staff to close the door after each use.

  2. 2. Power cut

    You can check this

    Signs: Excursion lines up with an outage, logger or controller shows a power-fail event.

    Fix: Keep the door closed during outages and follow your contingency plan. Backup power or units designed to hold temperature during outages are worth considering.

  3. 3. Vials too close to the cold source

    You can check this

    Signs: Cold excursion or frozen vials near the back wall, the evaporator outlet or the bottom of the unit.

    Fix: Store vaccines in the zones your procedures specify, away from cold walls and air outlets, with space for air to circulate.

  4. 4. Setpoint changed or controller fault

    Technician job

    Signs: Temperature consistently high or low, setpoint different from normal, display disagreeing with a calibrated logger.

    Fix: Restore the correct setpoint if your procedures allow and inform your supervisor. A technician should check the controller and sensor.

  5. 5. Unit in a hot room or near heat

    You can check this

    Signs: Warm excursions on hot afternoons, unit near a window or without ventilation.

    Fix: Relocate to a cooler, ventilated position with proper clearances, and clean the condenser with power isolated.

  6. 6. Refrigeration fault

    Technician job

    Signs: Temperature drifting despite a closed door and stable power, compressor or fan not running.

    Fix: Call a technician and move all stock to working storage.

When to call a technician

Call a technician for any excursion caused by an equipment fault, and keep the affected unit out of vaccine use until it has been repaired and has shown stable temperatures on a logger. Domestic refrigerators are not suitable for vaccine storage; use purpose-built medical refrigeration that meets your programme's requirements. The decision on the vaccines themselves always follows your programme rules.

Isolate power before cleaning or moving a refrigerator. Do not attempt repairs yourself. If the unit uses hydrocarbon refrigerant (R290 or R600a), only trained technicians should work on it.

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