Von Hotpoint fridge repair in Githurai.

A traditional compressor switches fully on and fully off. An inverter compressor changes its speed to suit the cooling needed. It runs slowly most of the time, which is quieter and uses less power, and it speeds up when the fridge needs to cool down.

To do that it needs a control board, called the inverter board, that converts the power and drives the compressor. The board is the weak point, because it dislikes surges and heat. When a board fails, the compressor does not start, even though the compressor itself may be fine.

That is why we test the board, the wiring and the compressor separately. A board can sometimes be repaired and sometimes needs replacing with a matching part. A voltage guard and a clean condenser are the best protection for an inverter fridge.

You call or WhatsApp us with what the fridge is doing and a photo of the model sticker. We tell you when a technician can come and how the visit fee works. The technician arrives, listens to the fridge, measures the temperature in both sections and checks the obvious causes in order.

When the fault is found, you are told what it is, shown the worn part where possible and given the full price for parts and labour before anything is changed. Nothing is done without your agreement. If a part has to be ordered, we tell you how long it will take.

After the repair, the fridge is left running and checked to confirm it is pulling down to temperature. Before we leave, we explain what failed and how to avoid it next time. If the fridge is not worth repairing, we say so, and we can collect an old fridge for responsible recycling.

A fridge does not make cold. It moves heat. Inside the sealed pipework there is a refrigerant gas. The compressor squeezes the gas, which makes it hot, and the hot gas flows through the coil at the back or underneath, called the condenser, where it gives its heat to the room. The gas turns to a liquid, passes through a very thin tube that drops its pressure, and arrives in the cold coil inside the fridge, the evaporator, where it turns back to a gas and soaks up heat from the food. Then it returns to the compressor and the cycle repeats.

That is why the back of a fridge feels warm and why a fridge squeezed into a cabinet struggles. If the heat cannot leave, the cycle slows and the compressor runs for longer. It is also why gas does not get used up: it travels round in a closed loop. When a fridge is low on gas there is a leak, and the leak has to be found and sealed first.

In a no-frost fridge a fan blows air over the evaporator and into the compartments, and a small heater melts the frost off the coil a few times a day. Most cooling faults come from these supporting parts, the fan, the heater, the sensor and the board, long before the compressor itself fails.

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.