Aircon Not Cold? 7 Common Causes and How to Fix Them
Aircon running but not cold? Check these 7 common causes – from dirty filters to low refrigerant gas – and learn what you can fix yourself.
By SPMM Group ·
Few things are worse on a hot Singapore night than an aircon that runs but doesn't cool. Before you call for help, check these common causes – some take two minutes to fix.
1. Wrong mode or temperature
Make sure the remote is on Cool (snowflake icon), not Fan or Dry, and set below the room temperature. A weak remote battery can also stop settings from reaching the unit.
2. Dirty air filter
A clogged filter blocks airflow, so less cold air reaches the room. Slide out the filters, rinse them with water, let them dry fully and refit. If they are very dirty, the coil behind them probably needs a general service too.
3. Dirty or mouldy coil
Dirt on the indoor coil acts like a blanket and stops heat transfer. This needs a chemical wash – the most common fix for "it used to be colder".
4. Outdoor unit blocked or dirty
The outdoor condenser must release heat. Check that nothing is stored around it and that the fan is spinning. A dirty condenser coil needs a compressor wash.
5. Low refrigerant gas
If the unit is clean but still blowing cool-ish rather than cold air, the refrigerant may be low – usually due to a small leak. Our technician measures the pressure (PSI) and tops up as needed. A gas top-up costs $50–$120 depending on the PSI level.
6. Room too big for the BTU
A 9,000 BTU unit in a large living room will run non-stop and never quite cool it. See our BTU guide.
7. Electrical or compressor fault
If the outdoor unit doesn't start at all, or trips the power, switch it off and call a technician – don't keep restarting it.
When to call us
If cleaning the filters doesn't help, WhatsApp us on +65 8078 4898 with a short description. We'll recommend the right service so you don't pay for one you don't need. Book online.