You've just had your AC cleaned and expected the room to feel noticeably cooler, but nothing much changed. This happens more often than you'd think, and the reason is almost never about the filter alone.
Here are 7 common causes of an AC that still isn't cold after cleaning, along with what you can do about each one.
1. Low or depleted refrigerant
Cleaning an AC removes dirt, it doesn't top up refrigerant. The refrigerant (freon) is what actually makes the air cold. If there's been a slow leak over months, no amount of cleaning will restore the cooling.
Signs of low refrigerant:
- Strong airflow but no real coldness
- The outdoor pipe frosts over or drips excessively
- The room takes an unusually long time to cool down
If this sounds familiar, the fix is a refrigerant recharge, not another cleaning. Leaving it too long can damage the compressor as well.
2. Evaporator coils weren't fully cleaned
The evaporator is the cold coil inside the indoor unit. If the technician only rinsed the filter without cleaning the coil fins thoroughly, the layer of grime blocking heat transfer is still there.
Units that haven't been serviced in a while often need a deeper clean than a standard wash. You can describe this in the notes field when booking so the technician knows what to expect.
3. Dirty outdoor condenser unit
The outdoor unit needs cleaning too. A condenser clogged with dust, mould, or dried leaves can't release heat efficiently, which means the whole cooling cycle suffers even if the indoor unit looks spotless.
Check that the area around the outdoor unit is clear and the fins aren't blocked.
4. A weakening compressor
The compressor is the heart of the system. Over time its performance drops due to age, overheating, or prolonged refrigerant loss. The clearest signs are unusual noise from the outdoor unit or the compressor cycling on and off erratically.
This isn't something a wash can fix. It needs a proper technical inspection.
5. Wrong mode or settings after restart
After a service, the AC is usually switched off and back on. It's easy for the remote to end up in "fan only" or "dry" mode instead of "cool", which means air blows out but the room stays warm.
Before assuming anything is broken, check the remote: confirm the mode is set to Cool, the temperature is between 18-24°C, and the fan speed makes sense for the room size.
6. AC capacity doesn't match the room
A 0.5 PK unit in a 25 m² room will always struggle, no matter how often it's cleaned. This isn't a fault, it's a mismatch. If the room has always felt borderline cold even when the AC was newer, capacity is likely the issue.
In this case it's worth looking into installing a unit with a more suitable capacity.
7. Air is escaping the room
An AC cools a sealed space. Large gaps under doors, poorly fitted windows, or open vents connected to outside mean cold air leaks out constantly and the unit can never keep up.
Once you've confirmed the AC itself is in good shape, check the room for draughts that could be undermining the cooling.
When to call a technician
If the remote settings are correct, the condenser isn't visibly blocked, and the AC still isn't cold after cleaning, the cause is almost certainly technical.
Two services cover the most common situations:
- Low refrigerant: book an AC refrigerant refill to restore the correct charge
- Deeper technical issues (compressor, coils, sensors): book AC repair for no cooling so a technician can diagnose and fix the problem on the spot
When booking, use the notes field to describe the situation: how long the AC has felt warm, whether there are any unusual sounds, and when refrigerant was last added. That context helps the technician arrive prepared.
Once a technician is matched to your booking, you can also chat with them directly to share more details before they head over.
How to prevent this from happening again
- Schedule an AC wash every three months, including the outdoor unit
- Ask the technician to check refrigerant pressure during routine servicing
- Keep doors and windows closed when the AC is running
- Keep a rough note of when refrigerant was last topped up — most systems need it every one to two years depending on conditions
An AC that stays warm after cleaning almost always has a fixable cause. Start with the simplest checks (remote mode, room gaps), and move on to a professional inspection if those don't explain it.