Aircon not cold? Checks to run before you call a technician

A warm aircon in Singapore feels like an emergency. Before you call anyone, a few minutes of checking can either fix the problem or give the technician better information, which tends to make the visit faster and the quote clearer. This guide sticks to checks that are safe for a homeowner.

Quick checks, in order

Work through these before calling.

Check	What to look for	If it is the cause
Mode and temperature	Unit set to cool, not fan or dry, and a sensible target temperature	Reset and wait 10 minutes
Remote batteries	Weak display or no response	Replace the batteries
Filters	Visibly clogged with dust	Wash and dry them fully
Airflow	Weak air from the indoor unit	Check filter and any blocked vents
Outdoor unit	Fan spinning, nothing blocking it	If it is not running, call a technician
Ice or frost	White buildup on pipes or indoor coil	Switch off and let it thaw, then call
Water	Drips from the indoor unit	Switch off, call a technician
Breaker	Tripped switch for the unit	Reset once only

If a breaker trips again after one reset, leave it and call a professional. Never open the casing, handle wiring or touch pipes.

What the symptoms often point to

Weak airflow with cool air: often a dirty filter or coil. A general service or chemical wash may solve it.

Air blows but is not cold: can mean low refrigerant, a faulty sensor, a failed capacitor or a compressor issue. This needs diagnosis, not cleaning.

Unit cools then stops: may be a tripped safety switch, a sensor fault or a blocked drain triggering a shutdown.

Water dripping indoors: typically a blocked or poorly sloped drain line.

Ice on the unit: low airflow or low refrigerant.

Treat these as pointers only. Several different faults produce the same symptoms, which is why diagnosis should come before a pricey fix. If a technician arrives and immediately recommends a chemical wash for a unit that is simply not cold, ask what the diagnosis was.

What to tell the technician

Having these ready makes the call quicker:

1. Brand, model and system type, which are on the indoor unit label.
2. How long the issue has been going on, and whether it got worse suddenly or slowly.
3. When it was last serviced.
4. What you have checked and what you saw.
5. Photos of any ice, leaks or error codes.

Ask about the inspection fee and whether it is deducted from the repair, so there is no surprise at the door.

When to call a technician straight away

Switch off and call if you see sparks, smell burning, hear loud grinding, find a tripped breaker that trips again, or notice water near electrical points. Do not keep running a unit in those conditions.

What not to do

Avoid spraying cleaning products into the unit, poking around inside the casing, or topping up gas with a DIY kit. Those steps can damage components or make a later diagnosis harder, and they can void a warranty. Keep to the filter, the remote and the breaker.

Also resist the urge to keep lowering the temperature setting. The compressor works the same way regardless of the number you set, and a very low target on a struggling unit only makes it run longer.

Finding help

Reviewers praise technicians who respond quickly, explain the fault clearly and avoid upselling. You can look through aircon repair contractors in Yishun and compare ratings. Our scoring method explains how, and the home page lists other categories.