Why is my fridge not cold enough in hot weather?

Almost every summer fridge complaint has the same root: the appliance can only work by dumping the heat it removes into the surrounding air, and everything that makes that harder shows up as a warm fridge. In winter there is enough margin to hide a dusty condenser or a tight cupboard. In August there is not, which is why faults that were always there suddenly appear.

Safety

Step by step

1. Measure before you diagnose.Put a fridge thermometer in a glass of water in the middle of the fridge and leave it a few hours. That gives you the food temperature rather than the air temperature, which swings every time the door opens. UK law requires chilled food to be kept at or below 8°C; aim for somewhere in the range of 0 to 5°C in practice. The dial on the fridge is a setting, not a measurement.
2. Check the clearances.Every fridge needs air to circulate around the back and above it to carry heat away. Manufacturers specify a gap, and a fridge pushed hard against a wall, boxed into a tight cupboard, or with items stored on top loses that path. This is the most common cause and the easiest to fix.
3. Clean the condenser coils.The black grille or coil at the back, or behind a kick panel underneath, rejects the heat. Dust and pet hair on it act as insulation, and a heavily furred condenser can lose a large part of its capacity. Unplug the appliance and brush and vacuum it carefully. Doing this once a year makes a real difference and almost nobody does it.
4. Look at where the fridge stands.A fridge beside an oven, against a boiler, in a conservatory, in direct sunlight from a window, or in a hot garage has to reject heat into air that is already hot. Some appliances also have a minimum ambient temperature rating that matters in an unheated garage in winter. If the position is the problem, moving it is the fix.
5. Test the door seal.Close the door on a piece of paper and pull — it should grip noticeably. Do that at several points around the door. A seal that is perished, twisted or has lost its magnetism lets warm humid air in continuously, which shows up as a fridge running constantly, ice forming and a compartment that will not come down.
6. Check you have not overfilled it.A fridge needs air to circulate internally. Packing it solid, especially in front of the vents at the back of the cabinet, leaves warm spots. A freezer is the opposite and likes to be full, which is where the confusion comes from.
7. Look at how it is being used.In summer the door gets opened far more, warm shopping goes in more often, and drinks are taken in and out constantly. Putting a big load of warm shopping away all at once raises the whole cabinet temperature for hours. Chill things quickly first where you can, and put away frozen and chilled items promptly rather than in stages.
8. Check for a blocked drain or heavy frost.A frosted-up evaporator or a blocked drain hole at the back of the fridge compartment restricts airflow and reduces cooling. Defrost it fully if there is significant ice, and clear the small drain hole with a cotton bud.
9. Distinguish a struggling fridge from a failing one.Running for longer in hot weather is normal and expected. Running continuously and still not reaching temperature after the checks above suggests a failing component — the fan, the thermostat, the compressor or a refrigerant leak — and that is an engineer's job. Refrigerant work is not a domestic repair.
10. Deal with the food while you sort the appliance.If the fridge has been above 8°C for hours in hot weather, treat high-risk chilled food accordingly rather than waiting to see. Move what you can to a cool box with ice packs while you work on it.

Tips

• A fridge thermometer costs very little and is the only way to know what is happening. The numbered dial tells you nothing about actual temperature.
• The door shelves are the warmest part of any fridge and swing most with every opening. Milk lives longer on a shelf at the back than in the door, whatever the moulding suggests.
• Letting hot food cool a little before refrigerating is sensible, but leaving it out for hours to cool completely is not — cool it quickly and get it in. The guide on cooling hot food covers the fast methods.
• A fridge that is more than about fifteen years old and struggling may simply be at the end of its life, and a modern one will use dramatically less electricity.
• If the kitchen itself is the problem, the cooling guides for the house apply — a fridge in a kitchen at thirty degrees is fighting a losing battle.

Common mistakes

• Turning the dial colder and assuming it is fixed — If the appliance cannot reject its heat, a colder setting simply makes it run continuously without reaching the target. Fix the airflow and the coils first.
• Never cleaning the condenser coils — Dust acts as insulation on exactly the surface designed to shed heat, and it is the most-skipped appliance maintenance job there is.
• Boxing a fridge tightly into a cupboard or against a wall — It needs a specified air gap to carry heat away. Without it the appliance runs hot, works harder, uses more electricity and fails sooner.
• Packing the fridge completely full — Internal air circulation is how the cold reaches everything. A freezer benefits from being full; a fridge does not.

If it doesn't work

Keeping on top of it

• Vacuum and brush the condenser coils (annually, before summer)
• Check the door seal with a paper strip (twice a year)
• Verify the temperature with a thermometer (seasonally)
• Clear the drain hole at the back of the fridge (when cleaning)

Questions people ask