Overview
An AC not cooling, whether a split air conditioner at home or a central aircon in an office, has one of twelve causes, and seven of them can be checked in ten minutes without tools. Dirty filters, a blocked outdoor unit and a wrong setting account for a large share of cases. The rest are failed parts: a capacitor, a fan motor, a sensor, a control board, a gas leak or the compressor.
This guide starts with the checks you can do yourself, then helps you find the cause from what the air conditioner is doing: running but not cooling, blowing warm air, blowing no air, or sitting silent outside. It ends with what each repair costs in Dubai.
AC not cooling: the short answer
If your AC has stopped cooling, suddenly or little by little, these are the causes in the order worth checking. The first five cost nothing to put right.
Fan or Dry mode, or a set temperature above the room temperature.
Blocked filters cut the airflow and can freeze the coil.
It cannot shed heat, so the unit cools weakly or cuts out.
The indoor unit may run on a separate supply while the outdoor unit has none.
From poor airflow or low gas.
The outdoor fan or compressor cannot start.
Indoor or outdoor.
Cooling fades over days or weeks.
The unit misreads the room and stops early.
Outdoor unit gets no signal, or the unit shows an error code.
Indoor or outdoor, coated beyond what a filter wash can help.
The least common and the most expensive.
Why is the AC not cooling in your case? The table further down matches what you can see and hear to the likely cause.
Seven checks to do before you call
These seven checks take about ten minutes and settle many AC cooling problems without a visit. To troubleshoot an air conditioner safely, stay outside the casing: look, listen and feel, and leave the covers on.
Set Cool, shown as a snowflake, and a temperature at least three degrees below the room. Fan mode moves air without cooling it. Dry mode cools only a little.
Fit fresh batteries and point the remote at the unit from close range. Cancel any timer or sleep setting, and check the unit beeps when you change the temperature.
Lift the front panel and slide the mesh filters out. If you cannot see light through them, wash them, dry them and refit them. On a central system, the filter sits behind the large return grille.
Hold a hand at the outlet. Strong flow of barely cool air is one problem. Weak flow is another. Note which.
Go and look. The fan should spin, you should hear the deeper hum of the compressor, and the air blowing out should feel hot. Clear away anything standing against it.
Find the AC breaker in the distribution board and the isolator switch near the outdoor unit. Reset a tripped breaker once. If it trips again, leave it off.
Look at the coil behind the filters and at the thin copper pipe outdoors. If there is frost or ice, switch to Fan mode for half an hour before anything else.
A temperature check that tells you a lot
With the unit in Cool for fifteen minutes, hold a kitchen thermometer in the air leaving the outlet, then at the intake where room air enters. A healthy split AC blows air about 8 to 12°C colder than the air it takes in. A difference of 4 or 5°C means the unit is running but not cooling properly. A normal difference with a warm room means the unit is working and the load is too much for it.
What not to do
Find the cause by what the AC is doing
What the unit does when you switch it on narrows twelve causes to two or three. Check the indoor unit and the outdoor unit separately, then find your row.
AC running but not cooling
When an AC is running but not cooling, with the indoor fan blowing and the outdoor unit working, the refrigeration circuit is moving too little heat. The causes, in order of likelihood, are dirty coils, low gas from a leak, an outdoor unit that cannot shed heat, and a worn compressor.
Split AC not cooling but fan is running
This is the commonest description we hear, and it covers two different faults. If the fan you mean is the indoor one, go outside and check the outdoor unit: when it is silent, the fault is electrical and is covered in the outdoor unit section below. If both units are running, the cause is in the table above.
Low gas is suspected far more often than it is found. Our AC gas refill page explains how to tell, and why a unit that needs gas has a leak that must be repaired.
AC blowing warm or hot air
An air conditioner blowing warm air indoors means the compressor is not running, or the unit is not in cooling mode. The indoor fan simply recirculates room air. An AC blowing hot air, hotter than the room, is in heating mode or has a stuck reversing valve.
Warm air for the first minute after start-up is normal on some models, while the compressor builds pressure.
Outdoor unit or compressor not working
When the outdoor unit is not working, the indoor unit blows air that is not cold. The cause is usually a small electrical part: the capacitor, the contactor, a fuse, or the cable between the two units. An AC compressor not working is far more often a compressor that cannot start than one that has failed.
The capacitor: small part, common fault
A capacitor gives the compressor and the fan motors the push they need to start. Heat ages it, and Dubai's summers are hard on capacitors. A swollen or weak one is among the cheapest AC repairs and one of the most frequent. If you are told the compressor is dead, ask whether the capacitor and contactor were tested first.
When to switch off straight away
Each of these can turn a small repair into a compressor replacement within minutes of running.
AC not blowing air, or weak airflow
An AC not blowing air, or blowing weakly, has an airflow fault and not a cooling fault. The air that does come out is often very cold. The causes are a blocked filter, an iced coil, a fan barrel packed with dust, a failed indoor fan motor, or, on a central system, a duct problem.
An AC not blowing cold air and an AC not blowing air at all are different faults. Tell the technician which one you have.
Ice on the coil and not cooling
An AC freezing up and not cooling has either too little air crossing the coil or too little gas inside it. Both make the coil colder than freezing. Ice then blocks the fins, airflow drops further, and cooling stops.
Run Fan mode for thirty minutes to an hour, with a towel below the unit.
And check nothing blocks the intake or the outlet.
With a medium or high fan speed.
If ice returns with clean filters, the coil is clogged or the gas is low.
Melting ice often overflows the drain pan. If water has started dripping, our guide to an AC leaking water explains what to do.
AC not cooling enough in the afternoon heat
An AC not cooling enough, one that cools well at night and struggles from noon to five, may be faulty, or may simply be at its limit. Air conditioners sold in the Gulf are rated at an outdoor temperature of 46°C. Above that their capacity falls, and on the hottest afternoons a healthy unit may hold a sunlit room at 25 or 26°C and no lower.
Signs it is the heat, not a fault
Signs it is a fault
What helps on the hottest days
If the unit has never held the room in summer, it may be too small. The sizing table on our AC installation page shows what a room of each size needs.
Not cooling after a service, gas refill, power cut or installation
When an AC stops cooling straight after something was done to it, that event is usually the cause. The table sets out the likely reason in each case, and who should put it right.
A new AC not cooling within its first weeks is covered by the installer's warranty for the fitting and the maker's warranty for the unit. Report it at once and in writing.
By type: split, inverter, central, window, portable and chilled water
The same causes apply to every type of air conditioning and HVAC system, but each type has faults of its own. Start with the one you have.
Flats on district cooling
Many Dubai towers cool each flat with chilled water from a central plant. If the fan blows and the air is not cold, the valve that lets chilled water into your unit has probably stuck shut, or the thermostat is not opening it. If neighbours have the same problem, it is the building's supply, and the building management or the cooling provider has to act. We repair the fan coil unit, its valve, actuator and thermostat.
One room not cooling
When one room stays warm while the rest of the home is cool, the cause depends on the system. With a split unit per room, that room's unit has a fault, so apply this guide to it. With a central system, the unit is fine and the air is not reaching the room.
Duct faults are found with a camera and an airflow check at each vent. See AC duct cleaning for duct inspection and repair.
What you can fix yourself, and what needs a technician
You can change settings, wash filters, clear the outdoor unit, reset a breaker once, and thaw ice. Everything inside the casing, and anything involving gas or mains wiring, needs a technician with a meter and gauges.
AC not cooling repair cost in Dubai
An AC not cooling repair in Dubai costs from AED 150 for a capacitor to AED 3,800 for a compressor, depending on the part. Our diagnostic visit is AED 100 plus VAT. The ranges below are 2026 market prices published by companies in the city, before VAT, and are not our fixed price list.
Most not-cooling repairs fall in the first seven rows. The technician tells you the cause and the price before starting.
Repair or replace?
Repair an AC when the unit is under about eight years old and the fault is a capacitor, motor, sensor, board or a leak at a joint. Consider replacing it when it is around ten years old and needs a compressor or a coil, or when it runs on R22 gas.
DEWA gives ten years as the optimal lifespan of an air conditioner. The age-by-age table on our AC repair page sets out the choice in more detail.
How to keep it cooling through summer
Most summer breakdowns are prevented by a service before the heat arrives and clean filters through the season.
Frequently asked questions
Why is my AC running but not cooling the house or apartment?
With both units running, the usual causes are dirty coils, low gas from a leak, or an outdoor unit that cannot shed heat. If the outdoor unit is silent, the fault is electrical.
Should I switch the AC off if it is not cooling?
Yes, if there is ice, a buzzing outdoor unit, a burning smell or rapid starting and stopping. Otherwise you can leave it in Fan mode while you wait.
Does not cooling always mean low gas?
No. Filters, coils and capacitors are more common causes. Gas is low only if it has leaked.
How long should an AC take to cool a room?
A correctly sized unit brings a closed bedroom to 24°C in about fifteen to thirty minutes. Much longer than that points to a fault, a heat problem or a unit that is too small.
Is the fault different on LG, Samsung, Daikin, Mitsubishi, Gree, Midea, Panasonic, O General, Haier, Hitachi or Carrier units?
The causes are the same on every brand. What differs is the error code, which the model's manual explains.
Why does my inverter AC cool slowly?
An inverter unit ramps its compressor up and down, so it can feel gentler than a fixed-speed unit. If it never reaches the set temperature, check for an error code and have the pressures tested.
My AC cools in the morning and not in the afternoon. Is it faulty?
Take the temperature difference at the unit. If it is 8°C or more, the unit is working and the room's heat load is the problem. If it is less, book a check.
Can a dirty filter really stop an AC cooling?
Yes. It cuts the airflow, the coil ices over, and the unit blows almost nothing.
Book an AC repair
If the seven checks have not brought the cooling back, book AC repair through the online form, by WhatsApp or on +971 55 209 9785. Tell us what the indoor and outdoor units are doing, whether there is ice, and any code on the display.
We come the same day, and within the hour for emergencies.
A technician can find the cause on site. The diagnostic is AED 100 plus VAT, and repairs carry a 1-month warranty.