Air conditioner no longer cooling: filters, outdoor unit or refrigerant after all?

Short answer: an air conditioner that no longer cools properly has dirty filters in most cases. That takes ten minutes and costs nothing in parts. If the problem persists, the second suspect is an outdoor unit that is not getting enough air, and only after that the refrigerant. The latter is never maintenance: an air conditioner does not use up refrigerant, so if the level is low, there is a leak.

Start with the filters

Behind the flap of the indoor unit are two filter mats. They catch dust from the room air and visibly clog up over a season. The result is less airflow, so less cooling, higher electricity consumption and eventually ice forming on the evaporator. Many people then think the refrigerant has run out, while the solution is behind the flap.

Standard filters can be rinsed with lukewarm water, left to dry completely and slid back in. Do this every two to three months during the season of use. Finer filters, such as activated carbon or air purification filters, are not washable and are replaced.

Part	Manufacturer number	Price
Daikin air filter	5016906	€ 14.95
Daikin air filter	5016282	€ 37.95
Haier 3M air purifier filter set	A0010808876	€ 67.45
Haier air filter	0010852454	€ 72.95

More filters can be found under filters in the catalogue.

The outdoor unit

The outdoor unit needs to be able to get rid of its heat. If it stands against a fence, under a closed canopy or is clogged with leaves and fluff, it cannot do so and the cooling capacity drops noticeably, precisely on the hottest days. Keep at least half a metre clear all round and carefully rinse the fins with a garden hose at low pressure, from the inside out, and never with a pressure washer.

Also check that the fan of the outdoor unit is turning. If it is not, the system will shut down on high pressure after a short time.

Settings that are wrong more often than you think

Is the unit really in cooling mode and not on fan or auto? Is the set temperature low enough, and the fan speed not on the lowest setting? Is there perhaps a timer or eco mode on that limits the output? And with multi-split systems: are all indoor units running in the same mode? Many systems cannot cool and heat at the same time, and then the first one switched on wins.

Refrigerant: never just top it up

If it still does not cool after checking the filters, outdoor unit and settings, there may be too little refrigerant in it. Haier reports this, for example, as code 16, refrigerant leak. Important to know: a sealed refrigerant circuit uses nothing. If the level is too low, there is a leak, and it must first be found and repaired. Simply topping up is like mopping with the tap running, and it is not permitted either.

Work on refrigerant may only be carried out by a certified refrigerant (F-gas) technician. A technician weighs the refrigerant, measures the pressure and finds the leak with a detector or with tracer dye.

What maintenance gets you

An air conditioner that is cleaned every year cools noticeably better and uses less electricity. Besides the filters, this covers the evaporator in the indoor unit, the condensate tray and the drain. Dirt there not only reduces cooling but also causes odours, and that is the point at which most people call for help. If water is running out of the indoor unit, read our guide on an air conditioner leaking water.

Is de airco aan vervanging toe? Bij · staan de mobiele en split-airco's met de levertijd per model.

Frequently asked questions

How often should I clean the filters?

Every two to three months during the season of use, and more often if you have pets or a lot of dust. It takes ten minutes and is the cheapest way to keep capacity and efficiency up to standard.

My air conditioner does cool, but much less than last year. What is wrong?

Usually a combination of dirty filters and a dirty outdoor unit. Check those two first; in practice that solves most complaints, without an engineer.

Ice is forming on the pipes of the indoor unit. Can I keep it running?

No, switch the unit off and let it defrost. Ice forming means too little airflow or too little refrigerant; keeping it running can damage the compressor.

Can I top up the refrigerant myself with a kit from the internet?

No. That is legally reserved for certified refrigerant (F-gas) technicians, and without the correct measurement you almost always fill it wrongly, which damages the system. What is more, the underlying leak simply remains.