An air conditioner that runs but does not cool is one of the most common complaints in warm, humid cities like Accra. The good news is that several causes are simple to check. The not-so-good news is that a few need a trained technician, and carrying on in the wrong way can turn a small fault into an expensive one.
Here are seven common causes, what you can safely check yourself, and the signs that tell you to stop and call for help.
In this guide
- Before you start: stay safe
- 7 common reasons an air conditioner is not cooling
- What you can safely do yourself
- When to call a technician
- A simple routine to keep your AC cooling
- Frequently asked questions
Before you start: stay safe
Switch the unit off at the remote and at the breaker before you clean or open anything. Do not open sealed parts of the system, and do not use high-pressure water on the metal fins of the coils, because it bends them and reduces airflow. If you smell burning, hear loud banging or see sparks, switch off and call a technician.
7 common reasons an air conditioner is not cooling
1. The settings are wrong
It sounds too simple, but check it first. Make sure the remote is on “cool” and not “fan” or “dry”, that the set temperature is below the room temperature, and that the fan speed is not on its lowest setting. If someone changed the mode, you may have a perfectly healthy unit.
2. The air filter is dirty or blocked
The filter stops dust from entering the unit. When it clogs, airflow drops and the room cools poorly. In a dusty city, and especially during the dry harmattan months, filters clog faster. Check yours every month and clean or replace it as the manufacturer advises. Many split-unit filters slide out and can be washed gently and dried fully before they go back.
3. The coils are dirty
Dirt on the indoor coil (the evaporator) and the outdoor coil (the condenser) stops the unit moving heat out of your room. Light surface dust on the outdoor unit can be brushed off carefully with the unit switched off. Deeper cleaning of the coils is a job for a technician, who can do it without bending the fins.
4. The outdoor unit cannot breathe
The outdoor unit needs space around it. Leaves, litter, a wall built too close or items stacked beside it block airflow, and the unit has to work harder for less cooling. Clear the area and keep it clear. Homes close to the coast may also see corrosion on outdoor units sooner, which is another reason a yearly check is worthwhile.
5. The evaporator coil is frozen
If you see ice on the indoor pipework or coil, or water suddenly drips where it did not before, the coil may have frozen. Poor airflow (often the filter) and low refrigerant are common causes. Switch the unit off and let the ice melt completely. If it freezes again after you have cleaned the filter, you need a technician.
6. Low refrigerant or a leak
Refrigerant is not “used up” like fuel. If the level is low, there is usually a leak. Topping it up without finding and fixing the leak only delays the problem. Refrigerant work needs the right tools and training, so this is always a job for a technician.
7. A failing compressor or electrical fault
The compressor is the heart of the system. Warning signs include the unit tripping the breaker, loud humming or banging, a burning smell, or the outdoor unit not starting while the indoor fan runs. Stop using the unit and call a technician. Running it can cause more damage.
A bonus cause: the unit and room do not match
Sometimes the unit is healthy but too small for the room, or the room gains a lot of heat from sun-facing windows, a kitchen or an open door. If your air conditioner has never cooled the space well, ask a technician to look at the size of the unit against the room.
What you can safely do yourself
- Check the mode, temperature and fan speed on the remote.
- Clean or replace the filter, and dry it fully before refitting.
- Clear leaves and debris from around the outdoor unit with the power off.
- Look for ice on the indoor unit and let it melt with the unit off.
- Check that the breaker has not tripped.
When to call a technician
- The unit still does not cool after the simple checks.
- It freezes up again, or water leaks from the indoor unit.
- You hear loud banging, grinding or screeching, or smell burning.
- The breaker trips when the unit starts.
- You suspect a refrigerant leak or a faulty compressor.
Regular servicing prevents many of these faults. Service guides generally recommend a professional inspection at least once a year, and more often if the unit works hard or sits in a dusty area. If yours is overdue, you can book an air conditioning service with us, or contact us to tell us what the unit is doing.
A simple routine to keep your AC cooling
- Check the filter monthly, and more often in the dusty harmattan months.
- Keep the area around the outdoor unit clear.
- Book a professional service at least once a year.
- Do not leave the unit running with doors and windows open.
- Act early. A weak unit that you keep running tends to get worse.
Our home maintenance checklist for Accra shows where an air conditioning check fits in the year.
Frequently asked questions
Why is my AC running but not cooling?
The most common causes are the wrong mode or temperature on the remote, a dirty filter, dirty coils, blocked airflow around the outdoor unit, a frozen coil, low refrigerant or a compressor fault. Start with the simple checks, then call a technician if the problem remains.
How often should I service my air conditioner?
A professional inspection at least once a year is the usual advice, and more often for units that run for long hours or in dusty conditions. Check and clean the filter yourself every month.
Why is my air conditioner leaking water?
A blocked drain line, a dirty filter that makes the coil freeze and then melt, or an installation problem can all cause leaks. If cleaning the filter does not stop it, have a technician look at it.
Can I top up the gas myself?
No. A low refrigerant level normally means a leak, and the system needs the leak found and repaired before it is recharged. This work needs trained technicians and the right equipment.