Air temperature naturally changes with compressor cycles, defrost, doors and deliveries.
In short: match the timing of each rise with operating events and check sensor location.
There is no universal ±2°C rule. Acceptable movement depends on control differential, defrost and product risk. Log several hours and compare an independent sensor. Frequent short cycling requires service diagnosis, not guessed parameter changes.
Symptoms
The temperature swings up and down by more than ±2 °C, and alarms trigger intermittently.
Causes and fixes
| Possible cause | How to check | Solution |
|---|---|---|
| Defrost too frequent or too long | Note the timing — temperature rises sharply during each defrost. | Adjust defrost frequency and duration in the controller. |
| Door left open | Watch staff behaviour — temperature climbs whenever the door is open. | Fit a door alarm or auto-closer; train staff. See Door problems. |
| Hot product loaded | Temperature spikes right after fresh stock goes in. | Pre-cool product before loading; load in smaller batches. |
| Thermostat sensor poorly located | A sensor near the door or in the cold-air discharge reads unrepresentatively. | Relocate the sensor to a representative position, away from the door and direct airflow. |
| Short-cycling compressor | Compressor starts and stops in cycles shorter than ~5 minutes. | Check the thermostat differential setting; persistent short-cycling can signal a refrigeration fault — call a technician. |
What is normal vs. what is not
A modest, regular swing during scheduled defrost is expected. Repeated alarms or swings well beyond ±2 °C are not, and on a chilled room they can breach the ≤ 5 °C food-safety window even though the average looks fine (the ≤ 5 °C figure is best practice; national rules vary).
Related articles
- Cold room temperature problems: triage and overview
- Room not reaching target temperature
- Overcooling and product freezing
- Ice & condensation issues
- Door problems
- When to call a professional
For help diagnosing a persistent swing, contact [email protected].
