Hisense fridge disposal in Nairobi.

Almost every fridge has a sticker or metal plate inside, usually on a side wall or at the back of the fridge compartment. It tells a technician almost everything: the brand, the model number, the voltage and frequency, the type of gas the fridge uses and how much of it, and often the manufacturing date.

Take a clear photo of that plate before you call. With the model number we can check which thermostat, seal, fan or board fits, which saves time on the visit. The gas type matters too. Modern fridges often use R600a, a flammable gas used in small amounts, while older ones commonly use R134a. The two are not interchangeable, and a fridge must always be charged with the gas printed on its own plate.

If you cannot find the plate, look for a sticker behind the vegetable drawers, on the inside of the door frame or on the back of the cabinet. Send us whatever you can find and the brand, and we will help you identify the model.

Power cuts and surges are hard on fridges. When the supply returns it can arrive with a spike that damages the control board or the parts that start the compressor. Inverter fridges are the most sensitive, because a board sits between the plug and the compressor.

A good voltage guard, also called a fridge guard, delays the power coming back for a few minutes and cuts it if the voltage is too high or too low. It costs far less than a board repair. Choose one rated for the fridge, plug the fridge into it directly and avoid sharing the socket with a heater or an iron.

After any outage, wait a few minutes before switching the fridge on if you do not have a guard. Keep the door closed during the cut. A full fridge holds its cold for several hours if it is not opened, and a full freezer holds it for longer. Do not keep switching the fridge off and on at the wall; it puts strain on the compressor.

Bacteria multiply quickly above about five degrees. If the fridge side is warm, move milk, meat, fish and cooked food to the freezer or a cool box with ice, and keep the door closed as much as you can. If the freezer is still frozen, do not open it more than you need to.

As a rule of thumb, fresh meat, fish, dairy and cooked leftovers should not stay in a warm fridge for more than a few hours. Food that has thawed and warmed should not be refrozen if it has been warm for long. When in doubt, throw it out: a repair is cheaper than being ill.

Medicines that need refrigeration should be moved to a cool box and kept as cold as the label asks. If you are not sure whether something is still safe, check the instructions on the packaging or ask a pharmacist.

Many people ask for a gas refill as soon as a fridge stops cooling. In practice, a fridge uses no gas. It circulates the same sealed charge for its whole life. If the charge is low, the fridge has a leak, and a refill without finding the leak means paying again in a few weeks.

Most cooling faults are something else: a blocked air channel, a stopped fan, a dirty condenser, a failed defrost heater, a worn door seal, a start relay, a thermostat or a board. These are found with a few tests, and they are usually cheaper to put right than a gas job.

When the tests point to a leak, we find it first, usually at a joint, a pipe that has rubbed or a corroded coil, repair it, pull a vacuum to remove air and moisture and then charge the exact gas the fridge was built for, by weight. That is the only way a gas job lasts.

A freezer with thick ice works harder and holds less. If your freezer is not no-frost, defrost it when the ice is a few millimetres thick. Switch it off at the wall, empty the contents into a cool box, and open the door. Put towels underneath to catch the water.

Never use a knife, a screwdriver or any sharp tool to chip the ice. The cooling pipes run very close to the surface, and a puncture lets out the gas and ruins the freezer. A bowl of warm water placed inside speeds things up, and a hairdryer on a low setting held at a distance can help, if you keep it away from water.

Wipe the inside dry before switching on again, and give the fridge a few hours to cool before refilling it. If ice builds up again within weeks, the door seal or the defrost system needs a technician.

Cold air has to move. Pack the shelves loosely enough that air can circulate, and never block the vents at the back or on the ceiling of the compartment. Keep the bulky items on the shelves and leave the door bins for things that tolerate warmth.

Raw meat and fish belong on the lowest shelf in sealed containers, so they cannot drip onto other food. Dairy and cooked food go in the middle. Fruit and vegetables belong in the drawers, where the humidity is higher.

Let hot food cool to room temperature before putting it in. Hot pots warm the fridge, force the compressor to work and bring in moisture that turns into frost. Cover liquids, because uncovered liquids add moisture to the air.

The condenser coil releases the heat the fridge removes from the food. On older fridges it is a grille on the back; on newer ones it may be a coil under the fridge behind a kick plate. Dust and kitchen grease form a blanket on it, which traps the heat.

Unplug the fridge before you start. Use a soft brush or the brush attachment of a vacuum cleaner to lift the dust, then a damp cloth for grease. Clean the area around the compressor too, and remove dust from the fan if there is one. Do it every few months, or more often in a dusty kitchen.

A clean coil can make a noticeable difference in how long the compressor runs and how much power the fridge uses. It is one of the cheapest and most effective bits of maintenance you can do yourself.

The door seal, or gasket, keeps warm air out. Over time it hardens, cracks or loses its magnetic grip. A bad seal causes frost, water inside, longer running and a higher bill.

Try the paper test: close the door on a sheet of paper and pull it out. If it slides out with no resistance, the seal is not gripping there. Test several points around the door. Look for splits, hardened sections and mould along the folds.

Wiping the seal with warm soapy water sometimes restores the grip, because grease and sugar stop it sealing. If cleaning does not help, the seal needs replacing. A new seal must be fitted straight, and the door adjusted so it closes evenly, or the new seal will not fix the problem.

A good technician explains the fault before changing parts. They test, tell you what failed and why, and give you the price before work starts. They show you the old part if you ask. They are honest when a repair does not make sense.

Be wary of anyone who names a fault over the phone without seeing the fridge, who insists on a gas refill without finding a leak or who will not give a price until the work is done. Ask whether the visit fee is separate and what it covers.

It also helps if the technician works on fridges every day. Fridges are a sealed cooling system with their own tools, gases and habits, and a general handyman may not have the equipment to vacuum and charge a system properly.