Air con not blowing cold air?
Dirty filters and wrong settings are common causes, and quick to check.
What it usually means
Air conditioning not cooling usually means the unit can’t move heat out of the room as it should. A blocked filter or a wrong setting is often behind it, and you can check both yourself. If those aren’t the cause, an engineer needs to look at it.
Other causes
Five faults can stop a unit blowing cold air.
Dirty filters
Dirty filters choke the airflow, so the room cools slowly and the unit works harder. Your manual shows how to clean them.
Low refrigerant
Low refrigerant means a leak, because a sealed system doesn’t use up its gas. Topping it up without finding the leak isn’t a repair, and the work needs an F-gas engineer.
The wrong mode or settings
A unit on Fan or Dry mode won’t cool the room properly, and a unit on Heat will warm it. The set temperature also has to be below the room’s temperature.
Ice on the pipes
Ice on the pipes usually points to weak airflow or low refrigerant. Air conditioning freezing up needs a rest, so turn the unit off and let the ice melt. Don’t chip it away, because that can damage the pipes.
A blocked outdoor unit
An outdoor unit needs clear air to get rid of the heat. Leaves, bins or a cover around it can stop the unit cooling.
What you can check safely
Five safe checks cover the common causes. Turn the unit off before you touch the filters:
- Set the mode to Cool, and the temperature below the room’s.
- Check the remote’s batteries and any timer.
- Clean the filters, as your manual shows.
- Clear anything from around the outdoor unit.
- Close the windows and doors, then give it 30 minutes.
Don’t open the casing, or touch the wiring or the pipe joints. Those parts need an engineer.
When it needs an engineer
A unit needs an engineer once the safe checks haven’t helped, or if you see any of these:
- ice that comes back after it has melted
- water dripping from the indoor unit
- an error code or a flashing light
- a new noise or smell
How a repair visit works. A regular service can catch many of these early. What a service covers.
Cooling questions
Why is my air con freezing up?
Air con usually freezes up when too little warm air reaches the cold coil, often because of a dirty filter. Low refrigerant can do the same. Turn the unit off, and call an engineer if the ice comes back.
Does air con need re-gassing every year?
No. A sealed system keeps its refrigerant, so needing more means there’s a leak. An F-gas engineer should find and fix the leak first.
Why does it cool one room but not another?
On a multi-split, each indoor unit can have its own fault, setting or dirty filter. Check that room’s filter and settings first. How multi-splits work.