Storing your Mestic MCCM-35 cool box properly over winter - My Mestic

November 28, 2025 Dean Horton

How to Store Your Cool Box Over Winter and Prevent Mould

After a busy season of touring, your cool box has probably seen its fair share of picnics, groceries and holiday treats. Taking a little time to clean and store it properly before winter can prevent mould, lingering odours and unnecessary wear.

1. Empty and defrost the cool box

Remove all food, drinks and ice packs. If your cool box has an ice compartment or any frost build-up, allow it to defrost naturally with the lid open.

2. Clean the interior thoroughly

Food spills and condensation are the main causes of mould and smells.

Wipe the interior with warm water and a mild, food-safe detergent.
Pay special attention to corners, seams and drain points.
Rinse with clean water and dry with a soft cloth.

3. Don’t forget the seals and lid

Rubber door seals can trap moisture and crumbs.

Gently clean seals with a damp cloth and mild detergent.
Check for damage or splits that could affect the seal next season.

4. Freshen with a gentle deodoriser if needed

If any odour remains, avoid harsh chemicals that could taint food later.

Place an open tub of bicarbonate of soda inside the cool box for a few days.
Alternatively, use a dedicated fridge deodoriser.

5. Store with the lid slightly open

Sealing a cool box completely can trap moisture inside.

Prop the lid open slightly using a folded cloth or purpose-made spacer.
Ensure children and pets cannot climb inside while it is stored.

6. Protect the exterior

Wipe down the outside of the cool box and check handles, hinges and catches.

Tighten any loose screws if accessible.
Store in a dry, shaded area away from direct sunlight or heat sources.

Ready for next season

These simple care steps help keep your Mestic cool box clean, hygienic and ready for the next adventure. When spring returns, you’ll be able to plug in, cool down and load up without any unpleasant surprises.

Why cool boxes grow mould in storage

A cool box is designed to seal when closed, which is exactly the wrong property for something being put away for four months. Whatever moisture is left inside has nowhere to go, and a few mild days are enough to turn that into mould.

The smell is the real problem. It gets into the insulation and the lid seal, and once it is there it is very difficult to remove. Prevention takes ten minutes. The cure is often a new cool box.

The three things that actually matter

Completely dry. Not towel-dry. Left open in a warm room for a day, including the drain, the seal channel and any removable basket.
Lid propped open. A folded cloth or a purpose-made spacer. This is the single most important step and the one most often skipped.
Stored somewhere dry. Not on a damp garage floor, and not inside a caravan that is itself sitting damp all winter.

Storing by cool box type

Thermoelectric models

Boxes such as the MTEC-25 (23 litres, 12V and 230V, 4 kg) and the MTEC-28 (26 litres, 4.5 kg) use a fan to move air. Check the vents are clear of dust before storage, because a blocked vent is the most common cause of poor performance when you next use it.

Both list a heating function as well as cooling, so they are worth keeping accessible over winter rather than burying at the back of the garage. Loaded with a hot meal they hold food at serving temperature on a cold drive.

Compressor models

Compressor boxes such as the MCCM-35 (35 litres, adjustable -22°C to +20°C, 38 dB, 17 kg) contain a refrigerant circuit. Store them upright, exactly as you would a domestic fridge. If one has travelled on its side, stand it upright for a few hours before switching it on again.

They are heavy — 17 kg for the MCCM-35 and 20 kg for the dual-zone MCCM-55 — so store them somewhere you can lift them from safely.

The cleaning routine before it goes away

Empty completely and remove any baskets or dividers.
Wash the interior with warm water and a mild detergent. Avoid bleach and solvents, which can damage the liner and leave a smell of their own.
For lingering odours, wipe out with bicarbonate of soda dissolved in warm water, then rinse.
Clean the seal channel specifically. Debris and moisture collect there and it is easily missed.
Dry everything thoroughly, then leave it open for a further day before storing.
Coil the cables loosely rather than tightly, and use the cable compartment if the model has one.
Leave a dry cloth or an open box of bicarbonate of soda inside to absorb any residual moisture.

Bringing it out in spring

Wipe the interior out before first use, even if it looks clean.
Run it empty for an hour to check it reaches temperature before you rely on it.
Check cables and plugs for damage, particularly if anything has been stacked on them.
Check the vents again for dust or cobwebs.