Air conditioning repair and regassing in London

| Symptom | Likely causes | |---|---| | Water dripping inside | blocked drain, failed condensate pump, unit not level, iced coil | | Not cooling | dirty filters or coils, wrong mode, low refrigerant from a leak, outdoor unit blocked | | Ice on pipes | low airflow, low refrigerant, very low set temperature | | Musty smell | dirty coil or drain tray, mould in the fan | | Noisy outdoor unit | loose fixings, fan damage, debris, failing compressor | | Error code | sensor, board, communication or protection fault: note the code |

The first two are the most common calls in London in the first hot week of the year, often on systems that missed a service.

Searches for "air con regas" are mostly about cars, where hoses and seals lose a little gas over time. A home split system is a sealed, brazed or flared copper circuit. If it is low on refrigerant, there is a leak somewhere, usually at a flare joint, a valve or a damaged pipe. Simply topping it up means paying for gas that will leak out again, and releasing refrigerant is harmful to the climate.

The right approach is to find the leak, repair it, pressure test the circuit, evacuate it and then recharge it to the manufacturer's weight. Under the F-gas rules this must be done by an engineer with an F-gas qualification working for a certified company. Ask for the company's certificate number and check it on the Refcom or F-Gas Register site.

In a London flat, a dripping indoor unit can soon stain the wall or leak into the flat below. Until an engineer arrives:

• turn the unit off at the remote and at its isolator if you know where it is
• put a towel and bowl under the unit
• do not pull the cover off or poke the drain
• tell your neighbour below if water may be getting through

Most drips come from a blocked drain or a failed condensate pump, which are usually straightforward to clear or replace.

If a system is old, uses the older R410A or an even older refrigerant, and needs a major part such as a compressor, replacement can make more sense than repair. Newer units are often quieter and more efficient. We will give you both options with honest reasons, and you choose. If you replace, the old refrigerant must be recovered properly, not vented.

A good description speeds up the repair. Note the make and model from the label on the indoor or outdoor unit, any error code or flashing light pattern, when the fault started, and whether it happens in cooling, heating or both. Say whether you can see ice, water or oil marks, and whether the outdoor unit fan is turning. A short video of the noise or the display is very helpful. If the system was installed by someone else, any paperwork showing the installer, refrigerant type and install date also helps.