A reefer (refrigerated) container consists of two separate systems: an insulated box and a refrigeration unit that cools it. Maintenance usually focuses only on the unit. Yet a significant share of temperature losses originates in the box.
The box: a silent point of loss
- Insulation damage. Reefer walls are filled with foam insulation. A hole in the outer or inner panel lets moisture into this foam. Wet insulation permanently loses its effectiveness and makes the unit run harder. Holes should be repaired promptly, even small ones.
- Interior lining. Interior panels (mostly stainless steel or aluminium) are damaged by forklift and cargo impacts. Damaged lining is a risk for both hygiene and insulation.
- Door seals. A torn or hardened seal lets cold air escape continuously. Look from the inside with the door closed: if light is getting in, cold air is getting out.
Floor and airflow
The reefer floor consists of T-shaped channels (T-floor). Cold air circulates under the cargo along these channels. Packaging waste, labels or cargo residue that fill the channels block the airflow and create hot spots in the container. The floor should be cleaned after every unloading.
Drainage
Water formed at the evaporator and washing water are discharged through the drain holes in the floor and the drain kits. Blocked drainage causes water to collect inside the container and, over time, corrosion and bad odours. Whether the drain kits are working should be checked regularly.
Refrigeration unit
- Pre-Trip Inspection (PTI). Before every loading, the unit is checked using the manufacturer’s test procedure. Sensitive cargo should not be loaded into a container that has not had a PTI.
- Condenser cleaning. A condenser coil coated in dust and salt cannot reject heat. The unit uses more energy and struggles to reach the set temperature.
- Data logging. The controller’s temperature records are the strongest evidence in any damage claim after the voyage. The records should be downloaded and kept regularly.
- Refrigerant. By law, all work involving refrigerant (charging, leak repair) must be carried out only by personnel certified for it.
Uskont carries out structural condition surveys and CSC examinations of reefer boxes. Servicing of the refrigeration unit is the job of the unit manufacturer’s authorised service partners. For a box examination, see our inspection service; to read a CSC plate, see our CSC guide.