Aircon not cold: causes and fixes

An aircon that is not cold usually has a simple cause: the thermostat or fan mode is wrong, the filter is clogged, or the outdoor unit is blocked. Check those three things first, and only then call a technician. A refrigerant leak, a unit that is low on refrigerant, or any electrical fault needs a professional, and you should not try to repair those yourself.

Taglish searchers often type ‘aircon hindi lumalamig’, which means the aircon is not getting cold. The steps below apply to split, window and inverter units in most Metro Manila homes. Switch the unit off before any cleaning, and stop at the first sign of a burning smell, sparks or water near the electrical parts.

Check the settings first

Start with the controls, because the cause is often a setting. Teko's guide on warm air lists incorrect thermostat settings and fan mode as common reasons an aircon blows warm air. It advises turning the fan mode to Auto rather than On. Carrier's troubleshooting article makes the same suggestion, recommending the Auto setting so the AC motor keeps working until it reaches the temperature you chose.

Set the temperature below the room temperature, and check that the remote is on cool rather than fan. If the air is still warm after the unit has had time to run on Auto, move on to the filter and the outdoor unit.

Clean the filter

A clogged filter is one of the most common reasons an aircon struggles to cool. Carrier advises washing the filter with warm soapy water and a soft brush to lift dust and fine debris, then making sure it is completely dry before you put it back. Never refit a damp filter.

Teko makes the same point from another angle. Weak airflow can come from clogged filters, so a monthly filter check is the cheapest habit that protects the cooling. If the filter is clean and the air is still weak, the problem is more likely inside the unit, where you cannot reach.

Clear the outdoor unit

The outdoor condenser sits in the open and collects leaves, dust and plant growth. Carrier's article says to clear debris and other objects such as plants around the unit so airflow is not obstructed. Before you go near the outdoor unit, switch the aircon off at the remote and make sure it is not running. Remove loose leaves and trim any vegetation that touches the unit, and leave enough space for air to move around it. Do not spray water into the outdoor unit's electrical box. If the unit or its wiring is wet, stop and call a technician.

A technician should wash the coil itself. Bent fins restrict airflow, and a proper coil wash needs the right tools and care, so a homeowner's hose is not the same job.

Check the breaker

If the outdoor unit does not run at all, check whether its breaker has tripped, but only with dry hands on a dry floor. Reset it once. If you are not sure it is safe, or the breaker trips again, or trips as soon as you reset it, stop and call a licensed electrician, because that points to an electrical fault. Our breaker guide explains what repeated trips usually mean.

When to call a technician

Some causes are not for the homeowner. Teko says a unit that is low on refrigerant cannot cool effectively, and it advises against trying to repair a suspected refrigerant or water leak yourself. Carrier's article says that if you suspect the aircon is leaking refrigerant, the best thing to do is contact a technician. Refrigerant top-ups and any gas work are technician work, done with the right equipment and not at home.

Call a technician as well if the fan will not start, the unit makes unusual noises, or the air stays warm after you have checked the settings, the filter and the outdoor unit. A technician can test the refrigerant, check the coil and look at the compressor, none of which a homeowner can do safely.

Stop and call straight away for these

If you can reach the unit's breaker safely, with dry hands on a dry floor, switch the unit off there. Otherwise, do not touch the unit, and call a licensed electrician at once if you smell burning, see scorching on a plug or switch, hear sparks, or find water near the electrical parts. Do not keep resetting a breaker that trips immediately. Bob Vila's guidance warns that resetting a breaker over and over can cause an arc flash, and that an electrician should take over if one reset does not fix the problem.

What cleaning costs and how often to do it

If the unit is simply dirty, a professional cleaning is the usual fix. aircon.ph lists ₱500 to ₱800 for a basic indoor clean of a split unit, and ₱800 to ₱1,500 when the outdoor unit is included. Chemical cleans cost more. Carrier says air conditioners must be cleaned at least three times a year to keep the filters free from dust and dirt, and Teko recommends a professional clean every three to four months for a home unit.

Keep the monthly filter check between visits. It costs nothing, and it shows you early when the airflow has started to drop. Write the date of each clean in your phone so you know when the next one is due.

How to describe the problem to a technician

Write down what the unit does: whether the fan runs, whether the air is warm from the start or only after a while, whether the outdoor unit runs, and what you changed before calling, such as the mode, the thermostat and the filter. A clear description shortens the visit, and it tells the technician which simple causes you have already ruled out. Note the date you first noticed the problem.

Costs before you agree a repair

A cleaning and a repair are different quotes. Ask whether the first visit is a diagnosis, whether that fee is waived if you go ahead, and whether refrigerant and parts are quoted separately. The cleaning ranges in this guide do not cover a repair, so ask for a separate quote before any work starts.

Frequently asked questions

Why is the fan working but the air is warm? A fan that runs without cooling often points to the thermostat or mode setting first, then a dirty filter. If the air stays warm after both are fixed, a refrigerant problem is likely, and a technician should check it.

Can I refill the refrigerant myself? No. Refrigerant top-ups and gas work are technician work. Teko advises against DIY repairs for a suspected leak.

Will a cleaning fix an aircon that is not cold? Sometimes. A dirty filter or coil reduces airflow, so a clean can restore the cooling. If the unit still blows warm air after a proper clean, the cause is more likely the refrigerant, the fan or an electrical part.

When should I call a technician? Call once the settings, the filter and the outdoor unit are checked and the air is still warm. Call at once for a burning smell, sparks or water near the electrical parts.